In psychology research, validity refers to the extent to which a test or measurement tool accurately measures what it’s intended to measure. It ensures that the research findings are genuine and not due to extraneous factors.
Validity can be categorized into different types based oninternal and external validity.
Internal and External Validity In Research
Internal validityrefers to whether the effects observed in a study are due to the manipulation of the independent variable and not some other confounding factor.
In other words, there is a causal relationship between theindependent and dependent variables.
External validityrefers to the extent to which the results of a study can be generalized to other settings (ecological validity), other people (population validity), and over time (historical validity).
Types of Validity In Psychology
Two main categories of validity are used to assess the validity of the test (i.e., questionnaire, interview, IQ test, etc.): Content and criterion.
Face Validity
Face validityis simply whether the test appears (at face value) to measure what it claims to. This is the least sophisticated measure of content-related validity, and is a superficial and subjective assessment based on appearance.
Tests wherein the purpose is clear, even to naïve respondents, are said to have high face validity. Accordingly, tests wherein the purpose is unclear have low face validity (Nevo, 1985).
It is important to select suitable people to rate a test (e.g., questionnaire, interview, IQ test, etc.). For example, individuals who actually take the test would be well placed to judge its face validity.
Also, people who work with the test could offer their opinion (e.g., employers, university administrators, employers). Finally, the researcher could use members of the general public with an interest in the test (e.g., parents of testees, politicians, teachers, etc.).
The face validity of a test can be considered a robust construct only if a reasonable level of agreement exists among raters.
Having face validity does not mean that a test really measures what the researcher intends to measure, but only in the judgment of raters that it appears to do so. Consequently, it is a crude and basic measure of validity.
A test item such as “I have recently thought of killing myself” has obvious face validity as an item measuring suicidal cognitions and may be useful when measuring symptoms of depression.
However, the implication of items on tests with clear face validity is that they are more vulnerable to social desirability bias. Individuals may manipulate their responses to deny or hide problems or exaggerate behaviors to present a positive image of themselves.
It is possible for a test item to lack face validity but still have general validity and measure what it claims to measure. This is good because it reduces demand characteristics and makes it harder for respondents to manipulate their answers.
For example, the test item “I believe in the second coming of Christ” would lack face validity as a measure of depression (as the purpose of the item is unclear).
This item appeared on the first version of The Minnesota Multiphasic Personality Inventory (MMPI) and loaded on the depression scale.
Because most of the original normative sample of theMMPIwere good Christians, only a depressed Christian would think Christ is not coming back. Thus, for this particular religious sample, the item does have general validity but not face validity.
Construct ValidityConstruct validityassesses how well a test or measure represents and captures an abstract theoretical concept, known as a construct. It indicates the degree to which the test accurately reflects the construct it intends to measure, often evaluated through relationships with other variables and measures theoretically connected to the construct.
Construct Validity
Construct validityassesses how well a test or measure represents and captures an abstract theoretical concept, known as a construct. It indicates the degree to which the test accurately reflects the construct it intends to measure, often evaluated through relationships with other variables and measures theoretically connected to the construct.
Construct validity does not concern the simple, factual question of whether a test measures an attribute.
Instead, it is about the complex question of whether test score interpretations are consistent with a nomological network involving theoretical and observational terms (Cronbach & Meehl, 1955).
To test for construct validity, it must be demonstrated that the phenomenon being measured actually exists. So, the construct validity of a test for intelligence, for example, depends on a model ortheory of intelligence.
Construct validity entails demonstrating the power of such a construct to explain a network of research findings and to predict further relationships.
The more evidence a researcher can demonstrate for a test’s construct validity, the better. However, there is no single method of determining the construct validity of a test.
Instead, different methods and approaches are combined to present the overall construct validity of a test. For example, factor analysis and correlational methods can be used.
Convergent validity
Convergent validityis a subtype of construct validity. It assesses the degree to which two measures that theoretically should be related are related.
For example, suppose there are two different scales used to measure self-esteem:
Scale A and Scale B. If both scales effectively measure self-esteem, then individuals who score high on Scale A should also score high on Scale B, and those who score low on Scale A should score similarly low on Scale B.
If the scores from these two scales show a strong positive correlation, then this provides evidence for convergent validity because it indicates that both scales seem to measure the same underlying construct of self-esteem.
Concurrent Validity (i.e., occurring at the same time)
Concurrent validityevaluates how well a test’s results correlate with the results of a previously established and accepted measure, when both are administered at the same time.
It helps in determining whether a new measure is a good reflection of an established one without waiting to observe outcomes in the future.
Very often, a new IQ or personality test might be compared with an older but similar test known to have good validity already.
Predictive ValidityPredictive validityassesses how well a test predicts a criterion that will occur in the future. It measures the test’s ability to foresee the performance of an individual on a related criterion measured at a later point in time. It gauges the test’s effectiveness in predicting subsequent real-world outcomes or results.
Predictive Validity
Predictive validityassesses how well a test predicts a criterion that will occur in the future. It measures the test’s ability to foresee the performance of an individual on a related criterion measured at a later point in time. It gauges the test’s effectiveness in predicting subsequent real-world outcomes or results.
For example, a prediction may be made on the basis of a new intelligence test that high scorers at age 12 will be more likely to obtain university degrees several years later. If the prediction is born out, then the test has predictive validity.
References
Cronbach, L. J., and Meehl, P. E. (1955) Construct validity in psychological tests.Psychological Bulletin, 52, 281-302.
Hathaway, S. R., & McKinley, J. C. (1943).Manual for the Minnesota Multiphasic Personality Inventory. New York: Psychological Corporation.
Kelley, T. L. (1927).Interpretation of educational measurements. New York: Macmillan.
Nevo, B. (1985).Face validity revisited.Journal of Educational Measurement, 22(4), 287-293.
Olivia Guy-Evans, MSc
BSc (Hons) Psychology, MSc Psychology of Education
Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.
Saul McLeod, PhD
BSc (Hons) Psychology, MRes, PhD, University of Manchester
Saul McLeod, PhD., is a qualified psychology teacher with over 18 years of experience in further and higher education. He has been published in peer-reviewed journals, including the Journal of Clinical Psychology.
