research on the validity

Frequently Asked Questions

What is reliability and validity in research.

Reliability in research refers to the consistency and stability of measurements or findings. Validity relates to the accuracy and truthfulness of results, measuring what the study intends to. Both are crucial for trustworthy and credible research outcomes.

What is validity?

Validity in research refers to the extent to which a study accurately measures what it intends to measure. It ensures that the results are truly representative of the phenomena under investigation. Without validity, research findings may be irrelevant, misleading, or incorrect, limiting their applicability and credibility.

What is reliability?

Reliability in research refers to the consistency and stability of measurements over time. If a study is reliable, repeating the experiment or test under the same conditions should produce similar results. Without reliability, findings become unpredictable and lack dependability, potentially undermining the study’s credibility and generalisability.

What is reliability in psychology?

In psychology, reliability refers to the consistency of a measurement tool or test. A reliable psychological assessment produces stable and consistent results across different times, situations, or raters. It ensures that an instrument’s scores are not due to random error, making the findings dependable and reproducible in similar conditions.

What is test retest reliability?

Test-retest reliability assesses the consistency of measurements taken by a test over time. It involves administering the same test to the same participants at two different points in time and comparing the results. A high correlation between the scores indicates that the test produces stable and consistent results over time.

How to improve reliability of an experiment?

• Standardise procedures and instructions.
• Use consistent and precise measurement tools.
• Train observers or raters to reduce subjective judgments.
• Increase sample size to reduce random errors.
• Conduct pilot studies to refine methods.
• Repeat measurements or use multiple methods.
• Address potential sources of variability.

What is the difference between reliability and validity?

Reliability refers to the consistency and repeatability of measurements, ensuring results are stable over time. Validity indicates how well an instrument measures what it’s intended to measure, ensuring accuracy and relevance. While a test can be reliable without being valid, a valid test must inherently be reliable. Both are essential for credible research.

Are interviews reliable and valid?

Interviews can be both reliable and valid, but they are susceptible to biases. The reliability and validity depend on the design, structure, and execution of the interview. Structured interviews with standardised questions improve reliability. Validity is enhanced when questions accurately capture the intended construct and when interviewer biases are minimised.

Are IQ tests valid and reliable?

IQ tests are generally considered reliable, producing consistent scores over time. Their validity, however, is a subject of debate. While they effectively measure certain cognitive skills, whether they capture the entirety of “intelligence” or predict success in all life areas is contested. Cultural bias and over-reliance on tests are also concerns.

Are questionnaires reliable and valid?

Questionnaires can be both reliable and valid if well-designed. Reliability is achieved when they produce consistent results over time or across similar populations. Validity is ensured when questions accurately measure the intended construct. However, factors like poorly phrased questions, respondent bias, and lack of standardisation can compromise their reliability and validity.

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What is the Significance of Validity in Research?

Introduction

• What is validity in simple terms?

Internal validity vs. external validity in research

Uncovering different types of research validity, factors that improve research validity.

In qualitative research , validity refers to an evaluation metric for the trustworthiness of study findings. Within the expansive landscape of research methodologies , the qualitative approach, with its rich, narrative-driven investigations, demands unique criteria for ensuring validity.

Unlike its quantitative counterpart, which often leans on numerical robustness and statistical veracity, the essence of validity in qualitative research delves deep into the realms of credibility, dependability, and the richness of the data .

The importance of validity in qualitative research cannot be overstated. Establishing validity refers to ensuring that the research findings genuinely reflect the phenomena they are intended to represent. It reinforces the researcher's responsibility to present an authentic representation of study participants' experiences and insights.

This article will examine validity in qualitative research, exploring its characteristics, techniques to bolster it, and the challenges that researchers might face in establishing validity.

At its core, validity in research speaks to the degree to which a study accurately reflects or assesses the specific concept that the researcher is attempting to measure or understand. It's about ensuring that the study investigates what it purports to investigate. While this seems like a straightforward idea, the way validity is approached can vary greatly between qualitative and quantitative research .

Quantitative research often hinges on numerical, measurable data. In this paradigm, validity might refer to whether a specific tool or method measures the correct variable, without interference from other variables. It's about numbers, scales, and objective measurements. For instance, if one is studying personalities by administering surveys, a valid instrument could be a survey that has been rigorously developed and tested to verify that the survey questions are referring to personality characteristics and not other similar concepts, such as moods, opinions, or social norms.

Conversely, qualitative research is more concerned with understanding human behavior and the reasons that govern such behavior. It's less about measuring in the strictest sense and more about interpreting the phenomenon that is being studied. The questions become: "Are these interpretations true representations of the human experience being studied?" and "Do they authentically convey participants' perspectives and contexts?"

Differentiating between qualitative and quantitative validity is crucial because the research methods to ensure validity differ between these research paradigms. In quantitative realms, validity might involve test-retest reliability or examining the internal consistency of a test.

In the qualitative sphere, however, the focus shifts to ensuring that the researcher's interpretations align with the actual experiences and perspectives of their subjects.

This distinction is fundamental because it impacts how researchers engage in research design , gather data , and draw conclusions . Ensuring validity in qualitative research is like weaving a tapestry: every strand of data must be carefully interwoven with the interpretive threads of the researcher, creating a cohesive and faithful representation of the studied experience.

While often terms associated more closely with quantitative research, internal and external validity can still be relevant concepts to understand within the context of qualitative inquiries. Grasping these notions can help qualitative researchers better navigate the challenges of ensuring their findings are both credible and applicable in wider contexts.

Internal validity

Internal validity refers to the authenticity and truthfulness of the findings within the study itself. In qualitative research , this might involve asking: Do the conclusions drawn genuinely reflect the perspectives and experiences of the study's participants?

Internal validity revolves around the depth of understanding, ensuring that the researcher's interpretations are grounded in participants' realities. Techniques like member checking , where participants review and verify the researcher's interpretations , can bolster internal validity.

External validity

External validity refers to the extent to which the findings of a study can be generalized or applied to other settings or groups. For qualitative researchers, the emphasis isn't on statistical generalizability, as often seen in quantitative studies. Instead, it's about transferability.

It becomes a matter of determining how and where the insights gathered might be relevant in other contexts. This doesn't mean that every qualitative study's findings will apply universally, but qualitative researchers should provide enough detail (through rich, thick descriptions) to allow readers or other researchers to determine the potential for transfer to other contexts.

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Looking deeper into the realm of validity, it's crucial to recognize and understand its various types. Each type offers distinct criteria and methods of evaluation, ensuring that research remains robust and genuine. Here's an exploration of some of these types.

Construct validity

Construct validity is a cornerstone in research methodology . It pertains to ensuring that the tools or methods used in a research study genuinely capture the intended theoretical constructs.

In qualitative research , the challenge lies in the abstract nature of many constructs. For example, if one were to investigate "emotional intelligence" or "social cohesion," the definitions might vary, making them hard to pin down.

To bolster construct validity, it is important to clearly and transparently define the concepts being studied. In addition, researchers may triangulate data from multiple sources , ensuring that different viewpoints converge towards a shared understanding of the construct. Furthermore, they might delve into iterative rounds of data collection, refining their methods with each cycle to better align with the conceptual essence of their focus.

Content validity

Content validity's emphasis is on the breadth and depth of the content being assessed. In other words, content validity refers to capturing all relevant facets of the phenomenon being studied. Within qualitative paradigms, ensuring comprehensive representation is paramount. If, for instance, a researcher is using interview protocols to understand community perceptions of a local policy, it's crucial that the questions encompass all relevant aspects of that policy. This could range from its implementation and impact to public awareness and opinion variations across demographic groups.

Enhancing content validity can involve expert reviews where subject matter experts evaluate tools or methods for comprehensiveness. Another strategy might involve pilot studies , where preliminary data collection reveals gaps or overlooked aspects that can be addressed in the main study.

Ecological validity

Ecological validity refers to the genuine reflection of real-world situations in research findings. For qualitative researchers, this means their observations , interpretations , and conclusions should resonate with the participants and context being studied.

If a study explores classroom dynamics, for example, studying students and teachers in a controlled research setting would have lower ecological validity than studying real classroom settings. Ecological validity is important to consider because it helps ensure the research is relevant to the people being studied. Individuals might behave entirely different in a controlled environment as opposed to their everyday natural settings.

Ecological validity tends to be stronger in qualitative research compared to quantitative research , because qualitative researchers are typically immersed in their study context and explore participants' subjective perceptions and experiences. Quantitative research, in contrast, can sometimes be more artificial if behavior is being observed in a lab or participants have to choose from predetermined options to answer survey questions.

Qualitative researchers can further bolster ecological validity through immersive fieldwork, where researchers spend extended periods in the studied environment. This immersion helps them capture the nuances and intricacies that might be missed in brief or superficial engagements.

Face validity

Face validity, while seemingly straightforward, holds significant weight in the preliminary stages of research. It serves as a litmus test, gauging the apparent appropriateness and relevance of a tool or method. If a researcher is developing a new interview guide to gauge employee satisfaction, for instance, a quick assessment from colleagues or a focus group can reveal if the questions intuitively seem fit for the purpose.

While face validity is more subjective and lacks the depth of other validity types, it's a crucial initial step, ensuring that the research starts on the right foot.

Criterion validity

Criterion validity evaluates how well the results obtained from one method correlate with those from another, more established method. In many research scenarios, establishing high criterion validity involves using statistical methods to measure validity. For instance, a researcher might utilize the appropriate statistical tests to determine the strength and direction of the linear relationship between two sets of data.

If a new measurement tool or method is being introduced, its validity might be established by statistically correlating its outcomes with those of a gold standard or previously validated tool. Correlational statistics can estimate the strength of the relationship between the new instrument and the previously established instrument, and regression analyses can also be useful to predict outcomes based on established criteria.

While these methods are traditionally aligned with quantitative research, qualitative researchers, particularly those using mixed methods , may also find value in these statistical approaches, especially when wanting to quantify certain aspects of their data for comparative purposes. More broadly, qualitative researchers could compare their operationalizations and findings to other similar qualitative studies to assess that they are indeed examining what they intend to study.

In the realm of qualitative research , the role of the researcher is not just that of an observer but often as an active participant in the meaning-making process. This unique positioning means the researcher's perspectives and interactions can significantly influence the data collected and its interpretation . Here's a deep dive into the researcher's pivotal role in upholding validity.

Reflexivity

A key concept in qualitative research, reflexivity requires researchers to continually reflect on their worldviews, beliefs, and potential influence on the data. By maintaining a reflexive journal or engaging in regular introspection, researchers can identify and address their own biases , ensuring a more genuine interpretation of participant narratives.

Building rapport

The depth and authenticity of information shared by participants often hinge on the rapport and trust established with the researcher. By cultivating genuine, non-judgmental, and empathetic relationships with participants, researchers can enhance the validity of the data collected.

Positionality

Every researcher brings to the study their own background, including their culture, education, socioeconomic status, and more. Recognizing how this positionality might influence interpretations and interactions is crucial. By acknowledging and transparently sharing their positionality, researchers can offer context to their findings and interpretations.

Active listening

The ability to listen without imposing one's own judgments or interpretations is vital. Active listening ensures that researchers capture the participants' experiences and emotions without distortion, enhancing the validity of the findings.

Transparency in methods

To ensure validity, researchers should be transparent about every step of their process. From how participants were selected to how data was analyzed , a clear documentation offers others a chance to understand and evaluate the research's authenticity and rigor .

Member checking

Once data is collected and interpreted, revisiting participants to confirm the researcher's interpretations can be invaluable. This process, known as member checking , ensures that the researcher's understanding aligns with the participants' intended meanings, bolstering validity.

Embracing ambiguity

Qualitative data can be complex and sometimes contradictory. Instead of trying to fit data into preconceived notions or frameworks, researchers must embrace ambiguity, acknowledging areas of uncertainty or multiple interpretations.

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Validity & Reliability In Research

A Plain-Language Explanation (With Examples)

By: Derek Jansen (MBA) | Expert Reviewer: Kerryn Warren (PhD) | September 2023

Validity and reliability are two related but distinctly different concepts within research. Understanding what they are and how to achieve them is critically important to any research project. In this post, we’ll unpack these two concepts as simply as possible.

This post is based on our popular online course, Research Methodology Bootcamp . In the course, we unpack the basics of methodology  using straightfoward language and loads of examples. If you’re new to academic research, you definitely want to use this link to get 50% off the course (limited-time offer).

Overview: Validity & Reliability

• The big picture
• Validity 101
• Reliability 101 
• Key takeaways

First, The Basics…

First, let’s start with a big-picture view and then we can zoom in to the finer details.

Validity and reliability are two incredibly important concepts in research, especially within the social sciences. Both validity and reliability have to do with the measurement of variables and/or constructs – for example, job satisfaction, intelligence, productivity, etc. When undertaking research, you’ll often want to measure these types of constructs and variables and, at the simplest level, validity and reliability are about ensuring the quality and accuracy of those measurements .

As you can probably imagine, if your measurements aren’t accurate or there are quality issues at play when you’re collecting your data, your entire study will be at risk. Therefore, validity and reliability are very important concepts to understand (and to get right). So, let’s unpack each of them.

What Is Validity?

In simple terms, validity (also called “construct validity”) is all about whether a research instrument accurately measures what it’s supposed to measure .

For example, let’s say you have a set of Likert scales that are supposed to quantify someone’s level of overall job satisfaction. If this set of scales focused purely on only one dimension of job satisfaction, say pay satisfaction, this would not be a valid measurement, as it only captures one aspect of the multidimensional construct. In other words, pay satisfaction alone is only one contributing factor toward overall job satisfaction, and therefore it’s not a valid way to measure someone’s job satisfaction.

Oftentimes in quantitative studies, the way in which the researcher or survey designer interprets a question or statement can differ from how the study participants interpret it . Given that respondents don’t have the opportunity to ask clarifying questions when taking a survey, it’s easy for these sorts of misunderstandings to crop up. Naturally, if the respondents are interpreting the question in the wrong way, the data they provide will be pretty useless . Therefore, ensuring that a study’s measurement instruments are valid – in other words, that they are measuring what they intend to measure – is incredibly important.

There are various types of validity and we’re not going to go down that rabbit hole in this post, but it’s worth quickly highlighting the importance of making sure that your research instrument is tightly aligned with the theoretical construct you’re trying to measure .  In other words, you need to pay careful attention to how the key theories within your study define the thing you’re trying to measure – and then make sure that your survey presents it in the same way.

For example, sticking with the “job satisfaction” construct we looked at earlier, you’d need to clearly define what you mean by job satisfaction within your study (and this definition would of course need to be underpinned by the relevant theory). You’d then need to make sure that your chosen definition is reflected in the types of questions or scales you’re using in your survey . Simply put, you need to make sure that your survey respondents are perceiving your key constructs in the same way you are. Or, even if they’re not, that your measurement instrument is capturing the necessary information that reflects your definition of the construct at hand.

If all of this talk about constructs sounds a bit fluffy, be sure to check out Research Methodology Bootcamp , which will provide you with a rock-solid foundational understanding of all things methodology-related. Remember, you can take advantage of our 60% discount offer using this link.

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What Is Reliability?

As with validity, reliability is an attribute of a measurement instrument – for example, a survey, a weight scale or even a blood pressure monitor. But while validity is concerned with whether the instrument is measuring the “thing” it’s supposed to be measuring, reliability is concerned with consistency and stability . In other words, reliability reflects the degree to which a measurement instrument produces consistent results when applied repeatedly to the same phenomenon , under the same conditions .

As you can probably imagine, a measurement instrument that achieves a high level of consistency is naturally more dependable (or reliable) than one that doesn’t – in other words, it can be trusted to provide consistent measurements . And that, of course, is what you want when undertaking empirical research. If you think about it within a more domestic context, just imagine if you found that your bathroom scale gave you a different number every time you hopped on and off of it – you wouldn’t feel too confident in its ability to measure the variable that is your body weight 🙂

It’s worth mentioning that reliability also extends to the person using the measurement instrument . For example, if two researchers use the same instrument (let’s say a measuring tape) and they get different measurements, there’s likely an issue in terms of how one (or both) of them are using the measuring tape. So, when you think about reliability, consider both the instrument and the researcher as part of the equation.

As with validity, there are various types of reliability and various tests that can be used to assess the reliability of an instrument. A popular one that you’ll likely come across for survey instruments is Cronbach’s alpha , which is a statistical measure that quantifies the degree to which items within an instrument (for example, a set of Likert scales) measure the same underlying construct . In other words, Cronbach’s alpha indicates how closely related the items are and whether they consistently capture the same concept . 

Recap: Key Takeaways

Alright, let’s quickly recap to cement your understanding of validity and reliability:

• Validity is concerned with whether an instrument (e.g., a set of Likert scales) is measuring what it’s supposed to measure
• Reliability is concerned with whether that measurement is consistent and stable when measuring the same phenomenon under the same conditions.

In short, validity and reliability are both essential to ensuring that your data collection efforts deliver high-quality, accurate data that help you answer your research questions . So, be sure to always pay careful attention to the validity and reliability of your measurement instruments when collecting and analysing data. As the adage goes, “rubbish in, rubbish out” – make sure that your data inputs are rock-solid.

Psst… there’s more!

This post is an extract from our bestselling short course, Methodology Bootcamp . If you want to work smart, you don't want to miss this .

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Statistics By Jim

Making statistics intuitive

Validity in Research and Psychology: Types & Examples

By Jim Frost 3 Comments

What is Validity in Psychology, Research, and Statistics?

Validity in research, statistics , psychology, and testing evaluates how well test scores reflect what they’re supposed to measure. Does the instrument measure what it claims to measure? Do the measurements reflect the underlying reality? Or do they quantify something else?

For example, does an intelligence test assess intelligence or another characteristic, such as education or the ability to recall facts?

Researchers need to consider whether they’re measuring what they think they’re measuring. Validity addresses the appropriateness of the data rather than whether measurements are repeatable ( reliability ). However, for a test to be valid, it must first be reliable (consistent).

Evaluating validity is crucial because it helps establish which tests to use and which to avoid. If researchers use the wrong instruments, their results can be meaningless!

Validity is usually less of a concern for tangible measurements like height and weight. You might have a cheap bathroom scale that tends to read too high or too low—but it still measures weight. For those types of measurements, you’re more interested in accuracy and precision . However, other types of measurements are not as straightforward.

Validity is often a more significant concern in psychology and the social sciences, where you measure intangible constructs such as self-esteem and positive outlook. If you’re assessing the psychological construct of conscientiousness, you need to ensure that the measurement instrument asks questions that evaluate this characteristic rather than, say, obedience.

Psychological assessments of unobservable latent constructs (e.g., intelligence, traits, abilities, proclivities, etc.) have a specific application known as test validity, which is the extent that theory and data support the interpretations of test scores. Consequently, it is a critical issue because it relates to understanding the test results.

Related post : Reliability vs Validity

Evaluating Validity

Researchers validate tests using different lines of evidence. An instrument can be strong for one type of validity but weaker for another. Consequently, it is not a black or white issue—it can have degrees.

In this vein, there are many different types of validity and ways of thinking about it. Let’s take a look at several of the more common types. Each kind is a line of evidence that can help support or refute a test’s overall validity. In this post, learn about face, content, criterion, discriminant, concurrent, predictive, and construct validity.

If you want to learn about experimental validity, read my post about internal and external validity . Those types relate to experimental design and methods.

Types of Validity

In this post, I cover the following seven types of validity:

• Face Validity : On its face, does the instrument measure the intended characteristic?
• Content Validity : Do the test items adequately evaluate the target topic?
• Criterion Validity : Do measures correlate with other measures in a pattern that fits theory?
• Discriminant Validity : Is there no correlation between measures that should not have a relationship?
• Concurrent Validity : Do simultaneous measures of the same construct correlate?
• Predictive Validity : Does the measure accurately predict outcomes?
• Construct Validity : Does the instrument measure the correct attribute?

Let’s look at these types of validity in more detail!

Face Validity

Face validity is the simplest and weakest type. Does the measurement instrument appear “on its face” to measure the intended construct? For a survey that assesses thrill-seeking behavior, you’d expect it to include questions about seeking excitement, getting bored quickly, and risky behaviors. If the survey contains these questions, then “on its face,” it seems like the instrument measures the construct that the researchers intend.

While this is a low bar, it’s an important issue to consider. Never overlook the obvious. Ensure that you understand the nature of the instrument and how it assesses a construct. Look at the questions. After all, if a test can’t clear this fundamental requirement, the other types of validity are a moot point. However, when a measure satisfies face validity, understand it is an intuition or a hunch that it feels correct. It’s not a statistical assessment. If your instrument passes this low bar, you still have more validation work ahead of you.

Content Validity

Content validity is similar to face validity—but it’s a more rigorous form. The process often involves assessing individual questions on a test and asking experts whether each item appraises the characteristics that the instrument is designed to cover. This process compares the test against the researcher’s goals and the theoretical properties of the construct. Researchers systematically determine whether each question contributes, and that no aspect is overlooked.

For example, if researchers are designing a survey to measure the attitudes and activities of thrill-seekers, they need to determine whether the questions sufficiently cover both of those aspects.

Learn more about Content Validity .

Criterion Validity

Criterion validity relates to the relationships between the variables in your dataset. If your data are valid, you’d expect to observe a particular correlation pattern between the variables. Researchers typically assess criterion validity by correlating different types of data. For whatever you’re measuring, you expect it to have particular relationships with other variables.

For example, measures of anxiety should correlate positively with the number of negative thoughts. Anxiety scores might also correlate positively with depression and eating disorders. If we see this pattern of relationships, it supports criterion validity. Our measure for anxiety correlates with other variables as expected.

This type is also known as convergent validity because scores for different measures converge or correspond as theory suggests. You should observe high correlations (either positive or negative).

Related posts : Criterion Validity: Definition, Assessing, and Examples and Interpreting Correlation Coefficients

Discriminant Validity

This type is the opposite of criterion validity. If you have valid data, you expect particular pairs of variables to correlate positively or negatively. However, for other pairs of variables, you expect no relationship.

For example, if self-esteem and locus of control are not related in reality, their measures should not correlate. You should observe a low correlation between scores.

It is also known as divergent validity because it relates to how different constructs are differentiated. Low correlations (close to zero) indicate that the values of one variable do not relate to the values of the other variables—the measures distinguish between different constructs.

Concurrent Validity

Concurrent validity evaluates the degree to which a measure of a construct correlates with other simultaneous measures of that construct. For example, if you administer two different intelligence tests to the same group, there should be a strong, positive correlation between their scores.

Learn more about Concurrent Validity: Definition, Assessing and Examples .

Predictive Validity

Predictive validity evaluates how well a construct predicts an outcome. For example, standardized tests such as the SAT and ACT are intended to predict how high school students will perform in college. If these tests have high predictive ability, test scores will have a strong, positive correlation with college achievement. Testing this type of validity requires administering the assessment and then measuring the actual outcomes.

Learn more about Predictive Validity: Definition, Assessing and Examples .

Construct Validity

A test with high construct validity correctly fits into the big picture with other constructs. Consequently, this type incorporates aspects of criterion, discriminant, concurrent, and predictive validity. A construct must correlate positively and negatively with the theoretically appropriate constructs, have no correlation with the correct constructs, correlate with other measures of the same construct, etc.

Construct validity combines the theoretical relationships between constructs with empirical relationships to see how closely they align. It evaluates the full range of characteristics for the construct you’re measuring and determines whether they all correlate correctly with other constructs, behaviors, and events.

As you can see, validity is a complex issue, particularly when you’re measuring abstract characteristics. To properly validate a test, you need to incorporate a wide range of subject-area knowledge and determine whether the measurements from your instrument fit in with the bigger picture! Researchers often use factor analysis to assess construct validity. Learn more about Factor Analysis .

For more in-depth information, read my article about Construct Validity .

Learn more about Experimental Design: Definition, Types, and Examples .

Nevo, Baruch (1985), Face Validity Revisited , Journal of Educational Measurement.

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April 21, 2022 at 12:05 am

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April 21, 2022 at 1:38 am

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March 14, 2023 at 1:27 am

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Validity in research: a guide to measuring the right things

Last updated

27 February 2023

Reviewed by

Cathy Heath

Short on time? Get an AI generated summary of this article instead

Validity is necessary for all types of studies ranging from market validation of a business or product idea to the effectiveness of medical trials and procedures. So, how can you determine whether your research is valid? This guide can help you understand what validity is, the types of validity in research, and the factors that affect research validity.

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• What is validity?

In the most basic sense, validity is the quality of being based on truth or reason. Valid research strives to eliminate the effects of unrelated information and the circumstances under which evidence is collected. 

Validity in research is the ability to conduct an accurate study with the right tools and conditions to yield acceptable and reliable data that can be reproduced. Researchers rely on carefully calibrated tools for precise measurements. However, collecting accurate information can be more of a challenge.

Studies must be conducted in environments that don't sway the results to achieve and maintain validity. They can be compromised by asking the wrong questions or relying on limited data. 

Why is validity important in research?

Research is used to improve life for humans. Every product and discovery, from innovative medical breakthroughs to advanced new products, depends on accurate research to be dependable. Without it, the results couldn't be trusted, and products would likely fail. Businesses would lose money, and patients couldn't rely on medical treatments. 

While wasting money on a lousy product is a concern, lack of validity paints a much grimmer picture in the medical field or producing automobiles and airplanes, for example. Whether you're launching an exciting new product or conducting scientific research, validity can determine success and failure.

• What is reliability?

Reliability is the ability of a method to yield consistency. If the same result can be consistently achieved by using the same method to measure something, the measurement method is said to be reliable. For example, a thermometer that shows the same temperatures each time in a controlled environment is reliable.

While high reliability is a part of measuring validity, it's only part of the puzzle. If the reliable thermometer hasn't been properly calibrated and reliably measures temperatures two degrees too high, it doesn't provide a valid (accurate) measure of temperature. 

Similarly, if a researcher uses a thermometer to measure weight, the results won't be accurate because it's the wrong tool for the job. 

• How are reliability and validity assessed?

While measuring reliability is a part of measuring validity, there are distinct ways to assess both measurements for accuracy. 

How is reliability measured?

These measures of consistency and stability help assess reliability, including:

Consistency and stability of the same measure when repeated multiple times and conditions

Consistency and stability of the measure across different test subjects

Consistency and stability of results from different parts of a test designed to measure the same thing

How is validity measured?

Since validity refers to how accurately a method measures what it is intended to measure, it can be difficult to assess the accuracy. Validity can be estimated by comparing research results to other relevant data or theories.

The adherence of a measure to existing knowledge of how the concept is measured

The ability to cover all aspects of the concept being measured

The relation of the result in comparison with other valid measures of the same concept

• What are the types of validity in a research design?

Research validity is broadly gathered into two groups: internal and external. Yet, this grouping doesn't clearly define the different types of validity. Research validity can be divided into seven distinct groups.

Face validity : A test that appears valid simply because of the appropriateness or relativity of the testing method, included information, or tools used.

Content validity : The determination that the measure used in research covers the full domain of the content.

Construct validity : The assessment of the suitability of the measurement tool to measure the activity being studied.

Internal validity : The assessment of how your research environment affects measurement results. This is where other factors can’t explain the extent of an observed cause-and-effect response.

External validity : The extent to which the study will be accurate beyond the sample and the level to which it can be generalized in other settings, populations, and measures.

Statistical conclusion validity: The determination of whether a relationship exists between procedures and outcomes (appropriate sampling and measuring procedures along with appropriate statistical tests).

Criterion-related validity : A measurement of the quality of your testing methods against a criterion measure (like a “gold standard” test) that is measured at the same time.

• Examples of validity

Like different types of research and the various ways to measure validity, examples of validity can vary widely. These include:

A questionnaire may be considered valid because each question addresses specific and relevant aspects of the study subject.

In a brand assessment study, researchers can use comparison testing to verify the results of an initial study. For example, the results from a focus group response about brand perception are considered more valid when the results match that of a questionnaire answered by current and potential customers.

A test to measure a class of students' understanding of the English language contains reading, writing, listening, and speaking components to cover the full scope of how language is used.

• Factors that affect research validity

Certain factors can affect research validity in both positive and negative ways. By understanding the factors that improve validity and those that threaten it, you can enhance the validity of your study. These include:

Random selection of participants vs. the selection of participants that are representative of your study criteria

Blinding with interventions the participants are unaware of (like the use of placebos)

Manipulating the experiment by inserting a variable that will change the results

Randomly assigning participants to treatment and control groups to avoid bias

Following specific procedures during the study to avoid unintended effects

Conducting a study in the field instead of a laboratory for more accurate results

Replicating the study with different factors or settings to compare results

Using statistical methods to adjust for inconclusive data

What are the common validity threats in research, and how can their effects be minimized or nullified?

Research validity can be difficult to achieve because of internal and external threats that produce inaccurate results. These factors can jeopardize validity.

History: Events that occur between an early and later measurement

Maturation: The passage of time in a study can include data on actions that would have naturally occurred outside of the settings of the study

Repeated testing: The outcome of repeated tests can change the outcome of followed tests

Selection of subjects: Unconscious bias which can result in the selection of uniform comparison groups

Statistical regression: Choosing subjects based on extremes doesn't yield an accurate outcome for the majority of individuals

Attrition: When the sample group is diminished significantly during the course of the study

Maturation: When subjects mature during the study, and natural maturation is awarded to the effects of the study

While some validity threats can be minimized or wholly nullified, removing all threats from a study is impossible. For example, random selection can remove unconscious bias and statistical regression. 

Researchers can even hope to avoid attrition by using smaller study groups. Yet, smaller study groups could potentially affect the research in other ways. The best practice for researchers to prevent validity threats is through careful environmental planning and t reliable data-gathering methods. 

• How to ensure validity in your research

Researchers should be mindful of the importance of validity in the early planning stages of any study to avoid inaccurate results. Researchers must take the time to consider tools and methods as well as how the testing environment matches closely with the natural environment in which results will be used.

The following steps can be used to ensure validity in research:

Choose appropriate methods of measurement

Use appropriate sampling to choose test subjects

Create an accurate testing environment

How do you maintain validity in research?

Accurate research is usually conducted over a period of time with different test subjects. To maintain validity across an entire study, you must take specific steps to ensure that gathered data has the same levels of accuracy. 

Consistency is crucial for maintaining validity in research. When researchers apply methods consistently and standardize the circumstances under which data is collected, validity can be maintained across the entire study.

Is there a need for validation of the research instrument before its implementation?

An essential part of validity is choosing the right research instrument or method for accurate results. Consider the thermometer that is reliable but still produces inaccurate results. You're unlikely to achieve research validity without activities like calibration, content, and construct validity.

• Understanding research validity for more accurate results

Without validity, research can't provide the accuracy necessary to deliver a useful study. By getting a clear understanding of validity in research, you can take steps to improve your research skills and achieve more accurate results.

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Internal Validity vs. External Validity in Research

What they tell us about the meaningfulness and trustworthiness of research

Verywell / Bailey Mariner

• Internal Validity
• External Validity

How do you determine whether a psychology study is trustworthy and meaningful? Two characteristics that can help you assess research findings are internal and external validity.

• Internal validity measures how well a study is conducted (its structure) and how accurately its results reflect the studied group.
• External validity relates to how applicable the findings are in the real world.

These two concepts help researchers gauge if the results of a research study are trustworthy and meaningful.

Conclusions are warranted

Controls extraneous variables

Eliminates alternative explanations

Focus on accuracy and strong research methods

Findings can be generalized

Outcomes apply to practical situations

Results apply to the world at large

Results can be translated into another context

What Is Internal Validity in Research?

Internal validity is the extent to which a research study establishes a trustworthy cause-and-effect relationship. This type of validity depends largely on the study's procedures and how rigorously it is performed.

Internal validity is important because once established, it makes it possible to eliminate alternative explanations for a finding. If you implement a smoking cessation program, for instance, internal validity ensures that any improvement in the subjects is due to the treatment administered and not something else.

Internal validity is not a "yes or no" concept. Instead, we consider how confident we can be with study findings based on whether the research avoids traps that may make those findings questionable. The less chance there is for "confounding," the higher the internal validity and the more confident we can be.

Confounding refers to uncontrollable variables that come into play and can confuse the outcome of a study, making us unsure of whether we can trust that we have identified the cause-and-effect relationship.

In short, you can only be confident that a study is internally valid if you can rule out alternative explanations for the findings. Three criteria are required to assume cause and effect in a research study:

• The cause preceded the effect in terms of time.
• The cause and effect vary together.
• There are no other likely explanations for the relationship observed.

Factors That Improve Internal Validity

To ensure the internal validity of a study, you want to consider aspects of the research design that will increase the likelihood that you can reject alternative hypotheses. Many factors can improve internal validity in research, including:

• Blinding : Participants—and sometimes researchers—are unaware of what intervention they are receiving (such as using a placebo on some subjects in a medication study) to avoid having this knowledge bias their perceptions and behaviors, thus impacting the study's outcome
• Experimental manipulation : Manipulating an independent variable in a study (for instance, giving smokers a cessation program) instead of just observing an association without conducting any intervention (examining the relationship between exercise and smoking behavior)
• Random selection : Choosing participants at random or in a manner in which they are representative of the population that you wish to study
• Randomization or random assignment : Randomly assigning participants to treatment and control groups, ensuring that there is no systematic bias between the research groups
• Strict study protocol : Following specific procedures during the study so as not to introduce any unintended effects; for example, doing things differently with one group of study participants than you do with another group

Internal Validity Threats

Just as there are many ways to ensure internal validity, a list of potential threats should be considered when planning a study.

• Attrition : Participants dropping out or leaving a study, which means that the results are based on a biased sample of only the people who did not choose to leave (and possibly who all have something in common, such as higher motivation)
• Confounding : A situation in which changes in an outcome variable can be thought to have resulted from some type of outside variable not measured or manipulated in the study
• Diffusion : This refers to the results of one group transferring to another through the groups interacting and talking with or observing one another; this can also lead to another issue called resentful demoralization, in which a control group tries less hard because they feel resentful over the group that they are in
• Experimenter bias : An experimenter behaving in a different way with different groups in a study, which can impact the results (and is eliminated through blinding)
• Historical events : May influence the outcome of studies that occur over a period of time, such as a change in the political leader or a natural disaster that occurs, influencing how study participants feel and act
• Instrumentation : This involves "priming" participants in a study in certain ways with the measures used, causing them to react in a way that is different than they would have otherwise reacted
• Maturation : The impact of time as a variable in a study; for example, if a study takes place over a period of time in which it is possible that participants naturally change in some way (i.e., they grew older or became tired), it may be impossible to rule out whether effects seen in the study were simply due to the impact of time
• Statistical regression : The natural effect of participants at extreme ends of a measure falling in a certain direction due to the passage of time rather than being a direct effect of an intervention
• Testing : Repeatedly testing participants using the same measures influences outcomes; for example, if you give someone the same test three times, it is likely that they will do better as they learn the test or become used to the testing process, causing them to answer differently

What Is External Validity in Research?

External validity refers to how well the outcome of a research study can be expected to apply to other settings. This is important because, if external validity is established, it means that the findings can be generalizable to similar individuals or populations.

External validity affirmatively answers the question: Do the findings apply to similar people, settings, situations, and time periods?

Population validity and ecological validity are two types of external validity. Population validity refers to whether you can generalize the research outcomes to other populations or groups. Ecological validity refers to whether a study's findings can be generalized to additional situations or settings.

Another term called transferability refers to whether results transfer to situations with similar characteristics. Transferability relates to external validity and refers to a qualitative research design.

Factors That Improve External Validity

If you want to improve the external validity of your study, there are many ways to achieve this goal. Factors that can enhance external validity include:

• Field experiments : Conducting a study outside the laboratory, in a natural setting
• Inclusion and exclusion criteria : Setting criteria as to who can be involved in the research, ensuring that the population being studied is clearly defined
• Psychological realism : Making sure participants experience the events of the study as being real by telling them a "cover story," or a different story about the aim of the study so they don't behave differently than they would in real life based on knowing what to expect or knowing the study's goal
• Replication : Conducting the study again with different samples or in different settings to see if you get the same results; when many studies have been conducted on the same topic, a meta-analysis can also be used to determine if the effect of an independent variable can be replicated, therefore making it more reliable
• Reprocessing or calibration : Using statistical methods to adjust for external validity issues, such as reweighting groups if a study had uneven groups for a particular characteristic (such as age)

External Validity Threats

External validity is threatened when a study does not take into account the interaction of variables in the real world. Threats to external validity include:

• Pre- and post-test effects : When the pre- or post-test is in some way related to the effect seen in the study, such that the cause-and-effect relationship disappears without these added tests
• Sample features : When some feature of the sample used was responsible for the effect (or partially responsible), leading to limited generalizability of the findings
• Selection bias : Also considered a threat to internal validity, selection bias describes differences between groups in a study that may relate to the independent variable—like motivation or willingness to take part in the study, or specific demographics of individuals being more likely to take part in an online survey
• Situational factors : Factors such as the time of day of the study, its location, noise, researcher characteristics, and the number of measures used may affect the generalizability of findings

While rigorous research methods can ensure internal validity, external validity may be limited by these methods.

Internal Validity vs. External Validity

Internal validity and external validity are two research concepts that share a few similarities while also having several differences.

Similarities

One of the similarities between internal validity and external validity is that both factors should be considered when designing a study. This is because both have implications in terms of whether the results of a study have meaning.

Both internal validity and external validity are not "either/or" concepts. Therefore, you always need to decide to what degree a study performs in terms of each type of validity.

Each of these concepts is also typically reported in research articles published in scholarly journals . This is so that other researchers can evaluate the study and make decisions about whether the results are useful and valid.

Differences

The essential difference between internal validity and external validity is that internal validity refers to the structure of a study (and its variables) while external validity refers to the universality of the results. But there are further differences between the two as well.

For instance, internal validity focuses on showing a difference that is due to the independent variable alone. Conversely, external validity results can be translated to the world at large.

Internal validity and external validity aren't mutually exclusive. You can have a study with good internal validity but be overall irrelevant to the real world. You could also conduct a field study that is highly relevant to the real world but doesn't have trustworthy results in terms of knowing what variables caused the outcomes.

Examples of Validity

Perhaps the best way to understand internal validity and external validity is with examples.

Internal Validity Example

An example of a study with good internal validity would be if a researcher hypothesizes that using a particular mindfulness app will reduce negative mood. To test this hypothesis, the researcher randomly assigns a sample of participants to one of two groups: those who will use the app over a defined period and those who engage in a control task.

The researcher ensures that there is no systematic bias in how participants are assigned to the groups. They do this by blinding the research assistants so they don't know which groups the subjects are in during the experiment.

A strict study protocol is also used to outline the procedures of the study. Potential confounding variables are measured along with mood , such as the participants' socioeconomic status, gender, age, and other factors. If participants drop out of the study, their characteristics are examined to make sure there is no systematic bias in terms of who stays in.

External Validity Example

An example of a study with good external validity would be if, in the above example, the participants used the mindfulness app at home rather than in the laboratory. This shows that results appear in a real-world setting.

To further ensure external validity, the researcher clearly defines the population of interest and chooses a representative sample . They might also replicate the study's results using different technological devices.

Setting up an experiment so that it has both sound internal validity and external validity involves being mindful from the start about factors that can influence each aspect of your research.

It's best to spend extra time designing a structurally sound study that has far-reaching implications rather than to quickly rush through the design phase only to discover problems later on. Only when both internal validity and external validity are high can strong conclusions be made about your results.

Andrade C. Internal, external, and ecological validity in research design, conduct, and evaluation .  Indian J Psychol Med . 2018;40(5):498-499. doi:10.4103/IJPSYM.IJPSYM_334_18

San Jose State University. Internal and external validity .

Kemper CJ. Internal validity . In: Zeigler-Hill V, Shackelford TK, eds. Encyclopedia of Personality and Individual Differences . Springer International Publishing; 2017:1-3. doi:10.1007/978-3-319-28099-8_1316-1

Patino CM, Ferreira JC. Internal and external validity: can you apply research study results to your patients?   J Bras Pneumol . 2018;44(3):183. doi:10.1590/S1806-37562018000000164

Matthay EC, Glymour MM. A graphical catalog of threats to validity: Linking social science with epidemiology .  Epidemiology . 2020;31(3):376-384. doi:10.1097/EDE.0000000000001161

Amico KR. Percent total attrition: a poor metric for study rigor in hosted intervention designs .  Am J Public Health . 2009;99(9):1567-1575. doi:10.2105/AJPH.2008.134767

Kemper CJ. External validity . In: Zeigler-Hill V, Shackelford TK, eds. Encyclopedia of Personality and Individual Differences . Springer International Publishing; 2017:1-4. doi:10.1007/978-3-319-28099-8_1303-1

Desjardins E, Kurtz J, Kranke N, Lindeza A, Richter SH. Beyond standardization: improving external validity and reproducibility in experimental evolution . BioScience. 2021;71(5):543-552. doi:10.1093/biosci/biab008

Drude NI, Martinez Gamboa L, Danziger M, Dirnagl U, Toelch U. Improving preclinical studies through replications .  Elife . 2021;10:e62101. doi:10.7554/eLife.62101

Michael RS. Threats to internal & external validity: Y520 strategies for educational inquiry .

Pahus L, Burgel PR, Roche N, Paillasseur JL, Chanez P. Randomized controlled trials of pharmacological treatments to prevent COPD exacerbations: applicability to real-life patients . BMC Pulm Med . 2019;19(1):127. doi:10.1186/s12890-019-0882-y

By Arlin Cuncic, MA Arlin Cuncic, MA, is the author of The Anxiety Workbook and founder of the website About Social Anxiety. She has a Master's degree in clinical psychology.

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Internal, External, and Ecological Validity in Research Design, Conduct, and Evaluation

Chittaranjan andrade.

Department of Psychopharmacology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

Reliability and validity describe desirable psychometric characteristics of research instruments. The concept of validity is also applied to research studies and their findings. Internal validity examines whether the study design, conduct, and analysis answer the research questions without bias. External validity examines whether the study findings can be generalized to other contexts. Ecological validity examines, specifically, whether the study findings can be generalized to real-life settings; thus ecological validity is a subtype of external validity. These concepts are explained using examples so that readers may understand why the consideration of internal, external, and ecological validity is important for designing and conducting studies, and for understanding the merits of published research.

DID CATIE HAVE EXTERNAL VALIDITY?

The answer is both yes and no. CATIE[ 1 ] was designed as an effectiveness study; that is, a study with relevance to real-world settings. The CATIE findings are relevant to clinical practice in the USA but are of questionable relevance in India. One reason is that, in the USA, where CATIE was conducted, the primary outcome, time to all-cause treatment discontinuation, is substantially patient-influenced, whereas in India, where families supervise treatment, it is largely caregiver-determined. Another and more important reason is that the healthcare delivery system in clinical practice is strikingly different in the two countries. Thus CATIE has good external validity for clinical practice in the USA but not in India.

RELIABILITY AND VALIDITY

Reliability and validity are concepts that are applied to instruments such as rating scales and screening tools. Validity describes how well an instrument does what it is supposed to do. For example, does an instrument that screens for depression do so with high sensitivity and specificity? Reliability describes the consistency with which results are obtained. For example, if an instrument that rates the severity of depression is administered to the same patient twice within the span of an hour, are the scores obtained closely similar? Different types of reliability and validity describe desirable psychometric properties of research and clinical instruments.[ 2 , 3 ] Validity can also be applied to laboratory and clinical studies, and to their findings, as well, as the sections below show.

INTERNAL VALIDITY

Internal validity examines whether the manner in which a study was designed, conducted, and analyzed allows trustworthy answers to the research questions in the study. For example, improper randomization, inadvertent unblinding of patients or raters, excessive use of rescue medication, and missing data can all undermine the fidelity of the results and conclusions of a randomized controlled trial (RCT). That is, the internal validity of the RCT is compromised. Internal validity is based on judgment and is not a computed statistic.

Internal validity examines the extent to which systematic error (bias) is present. Such systematic error can arise through selection bias, performance bias, detection bias, and attrition bias.[ 4 ] If internal validity is compromised, it can occasionally be improved, for example, by a modified plan of analysis. However, biases can be often fatal as, for example, if double-blind ratings were not obtained in an RCT.

EXTERNAL VALIDITY

External validity examines whether the findings of a study can be generalized to other contexts.[ 4 ] Studies are conducted on samples, and if sampling was random, the sample is representative of the population, and so the results of a study can validly be generalized to the population from which the sample was drawn. But results may not be generalizable to other populations. Thus external validity is poor for studies with sociodemographic restrictions; studies that exclude severely ill and suicidal patients, or patients with personality disorders, substance use disorders, and medical comorbidities; studies that disallow concurrent treatments; and so on. External validity is also limited in short-term studies of patients who need to be treated for months to years. External validity, like internal validity, is based on judgment and is not a computed statistic.

ECOLOGICAL VALIDITY

Ecological validity examines whether the results of a study can be generalized to real-life settings.[ 5 ] How is this different from external validity? External validity asks whether the findings of a study can be generalized to patients with characteristics that are different from those in the study, or patients who are treated in a different way, or patients who are followed up for longer durations. In contrast, ecological validity specifically examines whether the findings of a study can be generalized to naturalistic situations, such as clinical practice in everyday life. Ecological validity is, therefore, a subtype of external validity. The ecological validity of an instrument can be computed as a correlation between ratings obtained with that instrument and an appropriate measure in naturalistic practice or in everyday life. The ecological validity of a study is a judgment and is not a computed statistic.

Ecological validity was originally invoked in the context of laboratory studies that required to be generalized to real-life situations.[ 5 ] Thus, laboratory studies of the neuropsychological and psychomotor impairments produced by psychotropic drugs have poor ecological validity because what is studied in relaxed, rested, and healthy subjects tested in a controlled environment is very different from demands that stressed patients face in everyday life. In fact, these cognitive and psychomotor tests, especially when based on computerized tasks, have no parallel in everyday life. How much less ecological validity, then, would research in animal models of different neuropsychiatric states have for patients in clinical practice? This explains why drugs that work in animal models often fail in humans.[ 6 ]

On a parting note, a good understanding of the concepts of internal, external, and ecological validity is necessary to properly design and conduct studies and to evaluate the merits and applications of published research.

Financial support and sponsorship

Conflicts of interest.

There are no conflicts of interest.

Research validity in surveys relates to the extent at which the survey measures right elements that need to be measured. In simple terms, validity refers to how well an instrument as measures what it is intended to measure.

Reliability alone is not enough, measures need to be reliable, as well as, valid. For example, if a weight measuring scale is wrong by 4kg (it deducts 4 kg of the actual weight), it can be specified as reliable, because the scale displays the same weight every time we measure a specific item. However, the scale is not valid because it does not display the actual weight of the item.

Research validity can be divided into two groups: internal and external. It can be specified that “internal validity refers to how the research findings match reality, while external validity refers to the extend to which the research findings can be replicated to other environments” (Pelissier, 2008, p.12).

Moreover, validity can also be divided into five types:

1. Face Validity is the most basic type of validity and it is associated with a highest level of subjectivity because it is not based on any scientific approach. In other words, in this case a test may be specified as valid by a researcher because it may seem as valid, without an in-depth scientific justification.

Example: questionnaire design for a study that analyses the issues of employee performance can be assessed as valid because each individual question may seem to be addressing specific and relevant aspects of employee performance.

2. Construct Validity relates to assessment of suitability of measurement tool to measure the phenomenon being studied. Application of construct validity can be effectively facilitated with the involvement of panel of ‘experts’ closely familiar with the measure and the phenomenon.

Example: with the application of construct validity the levels of leadership competency in any given organisation can be effectively assessed by devising questionnaire to be answered by operational level employees and asking questions about the levels of their motivation to do their duties in a daily basis.

3. Criterion-Related Validity involves comparison of tests results with the outcome. This specific type of validity correlates results of assessment with another criterion of assessment.

Example: nature of customer perception of brand image of a specific company can be assessed via organising a focus group. The same issue can also be assessed through devising questionnaire to be answered by current and potential customers of the brand. The higher the level of correlation between focus group and questionnaire findings, the high the level of criterion-related validity.

4. Formative Validity refers to assessment of effectiveness of the measure in terms of providing information that can be used to improve specific aspects of the phenomenon.

Example: when developing initiatives to increase the levels of effectiveness of organisational culture if the measure is able to identify specific weaknesses of organisational culture such as employee-manager communication barriers, then the level of formative validity of the measure can be assessed as adequate.

5. Sampling Validity (similar to content validity) ensures that the area of coverage of the measure within the research area is vast. No measure is able to cover all items and elements within the phenomenon, therefore, important items and elements are selected using a specific pattern of sampling method depending on aims and objectives of the study.

Example: when assessing a leadership style exercised in a specific organisation, assessment of decision-making style would not suffice, and other issues related to leadership style such as organisational culture, personality of leaders, the nature of the industry etc. need to be taken into account as well.

My e-book,  The Ultimate Guide to Writing a Dissertation in Business Studies: a step by step assistance  offers practical assistance to complete a dissertation with minimum or no stress. The e-book covers all stages of writing a dissertation starting from the selection to the research area to submitting the completed version of the work within the deadline. John Dudovskiy

The 4 Types of Validity in Research Design (+3 More to Consider)

The conclusions you draw from your research (whether from analyzing surveys, focus groups, experimental design, or other research methods) are only useful if they’re valid.

How “true” are these results? How well do they represent the thing you’re actually trying to study? Validity is used to determine whether research measures what it intended to measure and to approximate the truthfulness of the results.

Unfortunately, researchers sometimes create their own definitions when it comes to what is considered valid.

• In quantitative research testing for validity and reliability is a given.
• However, some qualitative researchers have gone so far as to suggest that validity does not apply to their research even as they acknowledge the need for some qualifying checks or measures in their work.

This is wrong. Validity is always important – even if it’s harder to determine in qualitative research.

To disregard validity is to put the trustworthiness of your work in question and to call into question others’ confidence in its results. Even when qualitative measures are used in research, they need to be looked at using measures of reliability and validity in order to sustain the trustworthiness of the results.

What is validity in research?

Validity is how researchers talk about the extent to which results represent reality. Research methods, quantitative or qualitative, are methods of studying real phenomenon – validity refers to how much of that phenomenon they measure vs. how much “noise,” or unrelated information, is captured by the results.

Validity and reliability make the difference between “good” and “bad” research reports. Quality research depends on a commitment to testing and increasing the validity as well as the reliability of your research results.

Any research worth its weight is concerned with whether what is being measured is what is intended to be measured and considers how observations are influenced by the circumstances in which they are made.

The basis of how our conclusions are made plays an important role in addressing the broader substantive issues of any given study.

For this reason, we are going to look at various validity types that have been formulated as a part of legitimate research methodology.

Here are the 7 key types of validity in research:

• Face validity
• Content validity
• Construct validity
• Internal validity
• External validity
• Statistical conclusion validity
• Criterion-related validity

1. Face validity

Face validity is how valid your results seem based on what they look like. This is the least scientific method of validity, as it is not quantified using statistical methods.

Face validity is not validity in a technical sense of the term.  It is concerned with whether it seems like we measure what we claim.

Here we look at how valid a measure appears on the surface and make subjective judgments based on that.

For example,

• Imagine you give a survey that appears to be valid to the respondent and the questions are selected because they look valid to the administer.
• The administer asks a group of random people, untrained observers if the questions appear valid to them

In research, it’s never enough to rely on face judgments alone – and more quantifiable methods of validity are necessary to draw acceptable conclusions.  There are many instruments of measurement to consider so face validity is useful in cases where you need to distinguish one approach over another.

Face validity should never be trusted on its own merits.

2. Content validity

Content validity is whether or not the measure used in the research covers all of the content in the underlying construct (the thing you are trying to measure).

This is also a subjective measure, but unlike face validity, we ask whether the content of a measure covers the full domain of the content. If a researcher wanted to measure introversion, they would have to first decide what constitutes a relevant domain of content for that trait.

Content validity is considered a subjective form of measurement because it still relies on people’s perceptions for measuring constructs that would otherwise be difficult to measure.

Where content validity distinguishes itself (and becomes useful) through its use of experts in the field or individuals belonging to a target population. This study can be made more objective through the use of rigorous statistical tests.

For example, you could have a content validity study that informs researchers how items used in a survey represent their content domain, how clear they are, and the extent to which they maintain the theoretical factor structure assessed by the factor analysis.

3. Construct validity

A construct represents a collection of behaviors that are associated in a meaningful way to create an image or an idea invented for a research purpose. Construct validity is the degree to which your research measures the construct (as compared to things outside the construct).

Depression is a construct that represents a personality trait that manifests itself in behaviors such as oversleeping, loss of appetite, difficulty concentrating, etc.

The existence of a construct is manifest by observing the collection of related indicators.  Any one sign may be associated with several constructs.  A person with difficulty concentrating may have ADHD but not depression.

Construct validity is the degree to which inferences can be made from operationalizations (connecting concepts to observations) in your study to the constructs on which those operationalizations are based.  To establish construct validity you must first provide evidence that your data supports the theoretical structure.

You must also show that you control the operationalization of the construct, in other words, show that your theory has some correspondence with reality.

• Convergent Validity –  the degree to which an operation is similar to other operations it should theoretically be similar to.
• Discriminative Validity -– if a scale adequately differentiates itself or does not differentiate between groups that should differ or not differ based on theoretical reasons or previous research.
• Nomological Network –  representation of the constructs of interest in a study, their observable manifestations, and the interrelationships among and between these.  According to Cronbach and Meehl,  a nomological network has to be developed for a measure for it to have construct validity
• Multitrait-Multimethod Matrix –  six major considerations when examining Construct Validity according to Campbell and Fiske.  This includes evaluations of convergent validity and discriminative validity.  The others are trait method unit, multi-method/trait, truly different methodology, and trait characteristics.

4. Internal validity

Internal validity refers to the extent to which the independent variable can accurately be stated to produce the observed effect.

If the effect of the dependent variable is only due to the independent variable(s) then internal validity is achieved. This is the degree to which a result can be manipulated.

Put another way, internal validity is how you can tell that your research “works” in a research setting. Within a given study, does the variable you change affect the variable you’re studying?

5. External validity

External validity refers to the extent to which the results of a study can be generalized beyond the sample. Which is to say that you can apply your findings to other people and settings.

Think of this as the degree to which a result can be generalized. How well do the research results apply to the rest of the world?

A laboratory setting (or other research setting) is a controlled environment with fewer variables. External validity refers to how well the results hold, even in the presence of all those other variables.

6. Statistical conclusion validity

Statistical conclusion validity is a determination of whether a relationship or co-variation exists between cause and effect variables.

This type of validity requires:

• Ensuring adequate sampling procedures
• Appropriate statistical tests
• Reliable measurement procedures

This is the degree to which a conclusion is credible or believable.

7. Criterion-related validity

Criterion-related validity (also called instrumental validity) is a measure of the quality of your measurement methods.  The accuracy of a measure is demonstrated by comparing it with a measure that is already known to be valid.

In other words – if your measure has a high correlation with other measures that are known to be valid because of previous research.

For this to work you must know that the criterion has been measured well.  And be aware that appropriate criteria do not always exist.

What you are doing is checking the performance of your operationalization against criteria.

The criteria you use as a standard of judgment accounts for the different approaches you would use:

• Predictive Validity –  operationalization’s ability to predict what it is theoretically able to predict.  The extent to which a measure predicts expected outcomes.
• Concurrent Validity –  operationalization’s ability to distinguish between groups it theoretically should be able to.  This is where a test correlates well with a measure that has been previously validated.

When we look at validity in survey data we are asking whether the data represents what we think it should represent.

We depend on the respondent’s mindset and attitude to give us valid data.

In other words, we depend on them to answer all questions honestly and conscientiously. We also depend on whether they are able to answer the questions that we ask. When questions are asked that the respondent can not comprehend or understand, then the data does not tell us what we think it does.

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• Knowledge Base
• Methodology
• Reliability vs Validity in Research | Differences, Types & Examples

Reliability vs Validity in Research | Differences, Types & Examples

Published on 3 May 2022 by Fiona Middleton . Revised on 10 October 2022.

Reliability and validity are concepts used to evaluate the quality of research. They indicate how well a method , technique, or test measures something. Reliability is about the consistency of a measure, and validity is about the accuracy of a measure.

It’s important to consider reliability and validity when you are creating your research design , planning your methods, and writing up your results, especially in quantitative research .

Table of contents

Understanding reliability vs validity, how are reliability and validity assessed, how to ensure validity and reliability in your research, where to write about reliability and validity in a thesis.

Reliability and validity are closely related, but they mean different things. A measurement can be reliable without being valid. However, if a measurement is valid, it is usually also reliable.

What is reliability?

Reliability refers to how consistently a method measures something. If the same result can be consistently achieved by using the same methods under the same circumstances, the measurement is considered reliable.

What is validity?

Validity refers to how accurately a method measures what it is intended to measure. If research has high validity, that means it produces results that correspond to real properties, characteristics, and variations in the physical or social world.

High reliability is one indicator that a measurement is valid. If a method is not reliable, it probably isn’t valid.

However, reliability on its own is not enough to ensure validity. Even if a test is reliable, it may not accurately reflect the real situation.

Validity is harder to assess than reliability, but it is even more important. To obtain useful results, the methods you use to collect your data must be valid: the research must be measuring what it claims to measure. This ensures that your discussion of the data and the conclusions you draw are also valid.

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Reliability can be estimated by comparing different versions of the same measurement. Validity is harder to assess, but it can be estimated by comparing the results to other relevant data or theory. Methods of estimating reliability and validity are usually split up into different types.

Types of reliability

Different types of reliability can be estimated through various statistical methods.

Types of validity

The validity of a measurement can be estimated based on three main types of evidence. Each type can be evaluated through expert judgement or statistical methods.

To assess the validity of a cause-and-effect relationship, you also need to consider internal validity (the design of the experiment ) and external validity (the generalisability of the results).

The reliability and validity of your results depends on creating a strong research design , choosing appropriate methods and samples, and conducting the research carefully and consistently.

Ensuring validity

If you use scores or ratings to measure variations in something (such as psychological traits, levels of ability, or physical properties), it’s important that your results reflect the real variations as accurately as possible. Validity should be considered in the very earliest stages of your research, when you decide how you will collect your data .

• Choose appropriate methods of measurement

Ensure that your method and measurement technique are of high quality and targeted to measure exactly what you want to know. They should be thoroughly researched and based on existing knowledge.

For example, to collect data on a personality trait, you could use a standardised questionnaire that is considered reliable and valid. If you develop your own questionnaire, it should be based on established theory or the findings of previous studies, and the questions should be carefully and precisely worded.

• Use appropriate sampling methods to select your subjects

To produce valid generalisable results, clearly define the population you are researching (e.g., people from a specific age range, geographical location, or profession). Ensure that you have enough participants and that they are representative of the population.

Ensuring reliability

Reliability should be considered throughout the data collection process. When you use a tool or technique to collect data, it’s important that the results are precise, stable, and reproducible.

• Apply your methods consistently

Plan your method carefully to make sure you carry out the same steps in the same way for each measurement. This is especially important if multiple researchers are involved.

For example, if you are conducting interviews or observations, clearly define how specific behaviours or responses will be counted, and make sure questions are phrased the same way each time.

• Standardise the conditions of your research

When you collect your data, keep the circumstances as consistent as possible to reduce the influence of external factors that might create variation in the results.

For example, in an experimental setup, make sure all participants are given the same information and tested under the same conditions.

It’s appropriate to discuss reliability and validity in various sections of your thesis or dissertation or research paper. Showing that you have taken them into account in planning your research and interpreting the results makes your work more credible and trustworthy.

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Middleton, F. (2022, October 10). Reliability vs Validity in Research | Differences, Types & Examples. Scribbr. Retrieved 27 September 2024, from https://www.scribbr.co.uk/research-methods/reliability-or-validity/

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• Knowledge Base

Methodology

• Internal Validity in Research | Definition, Threats, & Examples

Internal Validity in Research | Definition, Threats & Examples

Published on May 1, 2020 by Pritha Bhandari . Revised on June 22, 2023.

Internal validity is the extent to which you can be confident that a cause-and-effect relationship established in a study cannot be explained by other factors.

Table of contents

Why internal validity matters, how to check whether your study has internal validity, trade-off between internal and external validity, threats to internal validity and how to counter them, other interesting articles, frequently asked questions about internal validity.

Internal validity makes the conclusions of a causal relationship credible and trustworthy. Without high internal validity, an experiment cannot demonstrate a causal link between two variables.

Once they arrive at the laboratory, the treatment group participants are given a cup of coffee to drink, while control group participants are given water. You also give both groups memory tests. After analyzing the results, you find that the treatment group performed better than the control group on the memory test.

For your conclusion to be valid, you need to be able to rule out other explanations (including control , extraneous , and confounding variables) for the results.

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There are three necessary conditions for internal validity. All three conditions must occur to experimentally establish causality between an independent variable A (your treatment variable) and dependent variable B (your response variable).

• Your treatment and response variables change together.
• Your treatment precedes changes in your response variables
• No confounding or extraneous factors can explain the results of your study.

In the research example above, only two out of the three conditions have been met.

• Drinking coffee and memory performance increased together.
• Drinking coffee happened before the memory test.
• The time of day of the sessions is an extraneous factor that can equally explain the results of the study.

Because you assigned participants to groups based on the schedule, the groups were different at the start of the study. Any differences in memory performance may be due to a difference in the time of day. Therefore, you cannot say for certain whether the time of day or drinking a cup of coffee improved memory performance.

That means your study has low internal validity, and you cannot deduce a causal relationship between drinking coffee and memory performance.

External validity is the extent to which you can generalize the findings of a study to other measures, settings or groups. In other words, can you apply the findings of your study to a broader context?

There is an inherent trade-off between internal and external validity ; the more you control extraneous factors in your study, the less you can generalize your findings to a broader context.

Threats to internal validity are important to recognize and counter in a research design for a robust study. Different threats can apply to single-group and multi-group studies.

Single-group studies

How to counter threats in single-group studies

Altering the experimental design can counter several threats to internal validity in single-group studies.

• Adding a comparable control group counters threats to single-group studies. If comparable control and treatment groups each face the same threats, the outcomes of the study won’t be affected by them.
• A large sample size counters testing, because results would be more sensitive to any variability in the outcomes and less likely to suffer from sampling bias .
• Using filler-tasks or questionnaires to hide the purpose of study also counters testing threats and demand characteristics .

Multi-group studies

How to counter threats in multi-group studies

Altering the experimental design can counter several threats to internal validity in multi-group studies.

• Random assignment of participants to groups counters selection bias and regression to the mean by making groups comparable at the start of the study.
• Blinding participants to the aim of the study counters the effects of social interaction.

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If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

• Normal distribution
• Degrees of freedom
• Null hypothesis
• Discourse analysis
• Control groups
• Mixed methods research
• Non-probability sampling
• Quantitative research
• Ecological validity

Research bias

• Rosenthal effect
• Implicit bias
• Cognitive bias
• Selection bias
• Negativity bias
• Status quo bias

I nternal validity is the degree of confidence that the causal relationship you are testing is not influenced by other factors or variables .

External validity is the extent to which your results can be generalized to other contexts.

The validity of your experiment depends on your experimental design .

There are eight threats to internal validity : history, maturation, instrumentation, testing, selection bias , regression to the mean, social interaction and attrition .

Attrition bias is a threat to internal validity . In experiments, differential rates of attrition between treatment and control groups can skew results.

This bias can affect the relationship between your independent and dependent variables . It can make variables appear to be correlated when they are not, or vice versa .

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Bhandari, P. (2023, June 22). Internal Validity in Research | Definition, Threats & Examples. Scribbr. Retrieved September 27, 2024, from https://www.scribbr.com/methodology/internal-validity/

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