Types of Validity

"Any research can be affected by different kinds of factors which, while extraneous to the concerns of the research, can invalidate the findings" (Seliger & Shohamy 1989, 95).

Let's take a look on the the most frequent uses of validity in the scientific method:

External Validity

External validity is about generalization: To what extent can an effect in research, be generalized to populations, settings, treatment variables, and measurement variables?

External validity is usually split into two distinct types, population validity and ecological validity and they are both essential elements in judging the strength of an experimental design.

Internal Validity

Internal validity is a measure which ensures that a researcher's experiment design closely follows the principle of cause and effect.

“Could there be an alternative cause, or causes, that explain my observations and results?”

Test Validity

Test validity is an indicator of how much meaning can be placed upon a set of test results.

Criterion Validity

Criterion Validity assesses whether a test reflects a certain set of abilities.

• Concurrent validity measures the test against a benchmark test and high correlation indicates that the test has strong criterion validity.

• Predictive validity is a measure of how well a test predicts abilities. It involves testing a group of subjects for a certain construct and then comparing them with results obtained at some point in the future.

Content Validity

Content validity is the estimate of how much a measure represents every single element of a construct.

Construct Validity

Construct validity defines how well a test or experiment measures up to its claims. A test designed to measure depression must only measure that particular construct, not closely related ideals such as anxiety or stress.

• Convergent validity tests that constructs that are expected to be related are, in fact, related.

• Discriminant validity tests that constructs that should have no relationship do, in fact, not have any relationship. (also referred to as divergent validity)

Face Validity

Face validity is a measure of how representative a research project is ‘at face value,' and whether it appears to be a good project.