Types of validity in research: content validity

In statistical terms, Validity is defined as the proportion of the true variance that is relevant for the purposes of the test.. By the term ‘relevant’ we refer to what is attributable to the variable, the characteristics that the test (1) measures. But do we know that there are various types of validity?

In this sense, generally the validity of a test is defined either by:

The relationship between your scores and some external criterion measure, or, The extent to which the test measures a specific hypothesized underlying trait or “construct.”

Validity in psychometric terms

In psychometric terms, Validity is a concept that has gone through a long evolutionary process. At first, Muñiz (1996) adopted validity with a specific position. This maintained that “a test is valid for what it correlates with.”

Now, validity is understood as a global evaluative judgment. In this judgment, empirical evidence and theoretical assumptions support the sufficiency and appropriateness of the interpretations not only of the items, but also of the way people respond as well as the context of the evaluation.

So, what is validated is not the proof. What is specifically validated are the inferences made from it. This has two consequences:

The person responsible for the validity of a test is no longer only its constructor, but also the user.The validity of a test is not established once and for all. It is the result of the collection of evidence and theoretical assumptions that occur in an evolutionary and continuous process. This includes all the experimental, statistical and philosophical questions through which scientific hypotheses and theories are evaluated (3).

In this context, the concept validity It refers to the adequacy, meaning, and usefulness of specific inferences made from test scores. Test validation is the process of accumulating evidence to support such inferences. Thus, validity is a unitary process. Although evidence can be accumulated in many ways, validity always refers to the degree to which that evidence supports the inferences made from the scores (4).

Types of evidence

In 1954, a committee chaired by LJ Cronbach established, commissioned by the American Psychological Association (APA), that lValidity was of four types. These are:

Content validity. Predictive validity. Concurrent validity. Construct validity.

It is currently agreed, from a scientific point of view, that the only admissible validity is construct validity (Messick, 1995).

Validity and its aspects

Within the study of validity, the evidence is related to five aspects:

He content (the relevance and representativeness of the test). noun (the theoretical reasons for the observed consistency of responses).Structural (internal configuration of the test and dimensionality).Generalization (the degree to which inferences made from the test can be generalized to other populations, situations, or tasks).External (relationships of the test with other tests and constructs).Consequence (ethical and social consequences of the test) (3).

Thus, within this validity we can understand other types of validity or strategies. As we have previously mentioned, these are content validity, predictive validity, concurrent validity and construct validity.

Types of validity: content validity

In this type of validity, the following question is answered. Are the items that make up the test really a representative sample of the domain of content or behavioral domain that interests us?

So that we understand each other, a domain or behavioral field is a hypothetical grouping of all possible items that cover a particular psychological area. For example, a vocabulary test should be an adequate sample of the domain of possible items in this area.

In this sense, Content validity is a “measure” of the adequacy of sampling. It is said “measurement” in quotes, since this type of validity consists of a series of estimates or opinions. These estimates do not provide a quantitative index of validity. (1)

This type of validity is mainly associated with performance tests. (mathematics test, history…). For its determination, the test questions are systematically compared with the behavioral domain of the postulated content.

For example, we have a list of 500 words that we expect students in a course to be able to spell correctly. So, their performance on these words will be important exclusively to test the student’s ability to spell the 500 words correctly. However, it will only have content validity to the extent that it provides an adequate sample of the 500 words it represents. (1)

If we select only easy or difficult wordsor words that represent only certain types of misspellings, we would be likely to get a very low content validity.

Conclusion: what is the usefulness of content validity?

Consequently, he key aspect in content validity is item sampling. In other words, content validity is capable of determining whether the sample of its items is representative of the universe or behavioral domain of items that it supposedly represents (1).

Thus, content validity is that type of validity that is linked to the test itself and what it aims to measure. For example, it will allow us know if the sample of test items is representative of the domain in mathematics that we want to evaluate. It is, therefore, an important concept both in statistics and in the use of psychological or performance tests.

By way of conclusion, the study of validity is an analysis of a metric test, in our case, since we are in psychology, psychometric whose conclusions refer to the degree to which said test measures what we want it to measure. Logically, The more validity a test has, in the absence of other analyzes – such as reliability -, the better it will be..

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