Validity - graphical overview

Face Validity

Does the test/questionnaire appear to test what it aims to test?

“Face validity” refers to whether the items appear to be valid to the test taker or test user

Superficial assessment if the measurement procedure used in a study appears to be a valid measure of a given variable

Content Validity

The extent to which the items reflect a specific domain of content

Is the sample of items representative for the domain in question?

Example 1: Do items of a math test cover all relevant mathematical operations (addition, subtraction, division, and their combinations)?

Example 2: Fitness test should contain elements of strenght, stamina, skill, motor coordination

Often a matter of judgment – Experts may be asked to rate the relevance and appropriateness of the items or questions

E.g., rate each item: very important / nice to know / not important

Criterion Validity

Concurrent validity: Degree to which a test corresponds to an external criterion that is known concurrently

Two measures in the study are taken at the same time and their scores are measured

Example: Correlation between IQ test scores of pupils and their currently obtained math grades

Predictive validity: Degree to which a test accurately predicts a criterion that will occur in the future

Example: Correlation between IQ assed at the age of 15 with grades at the university 7 years later

Construct Validity

Convergent validity

Examines the degree to which the operationalization is similar to other operationalizations that it theoretically should be similar to

Example: Assessing the convergent validity of a test of arithmetic skills

Correlate the scores on a test that is supposed to measure arithmetic ability with scores on other tests that purport to measure basic math ability

A strong correlation would be evidence of convergent validity

Discriminant validity

Examines the degree to which the operationalization is not similar to other operationalizations that it theoretically should be not be similar to

Examples: Assessing the discriminant validity of a test of arithmetic skills:

Correlate the scores of a test which is supposed to measure arithmetic ability with scores of tests of verbal ability, where low correlations would be evidence of discriminant validity

Average correlation between IQ tests and tests of attention: r≈.20

A side note on discriminant validity

Evidence for discriminant validity: Low or zero correlation

Discriminant correlations should be at least smaller than convergent correlations

Showing that two tests are negatively correlated does not imply discriminant validity

Because they are, in fact, related and we could use one test to predict scores of the other tests

Example: Correlation between an extraversion and an introversion scale: r = -.90, put differently, r2 = .81

81% shared variance

It is hard to distinguish between these constructs

Introversion is just the opposite of extraversion

This is actually an example of convergent validity!

Last changed15 days ago