LANGUAGE ASSESSMENT: TEST VALIDITY

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The characteristic of a good test :

Validity

alidity

            Validity is defined as the extent to which the instrument measures what it purports to measure. For example, a test that is used to screen applicants for a job is valid if its scores are directly related to future job performance. There are many different types of validity, including: content validity, face validity, criterion-related validity (or predictive validity), construct validity, factorial validity, concurrent validity, convergent validity and divergent (or discriminant validity).

1.      Content validity

            Content validity pertains to the degree to which the instrument fully assesses or measures the construct of interest. For example, say we are interested in evaluating employees’ attitudes toward a training program within an organization. We would want to ensure that our questions fully represent the domain of attitudes toward the training program. The development of a content valid instrument is typically achieved by a rational analysis of the instrument by raters (ideally 3 to 5) familiar with the construct of interest. Specifically, raters will review all of the items for readability, clarity and comprehensiveness and come to some level of agreement as to which items should be included in the final instrument.

2.      Face validity

            Face validity is a component of content validity and is established when an individual reviewing the instrument concludes that it measures the characteristic or trait of interest. For instance, if a quiz in this class comprised items that asked questions pertaining to research methods you would most likely conclude that it was face valid. In short, it looks as if it is indeed measuring what it is designed to measure.

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3.      Criterion-related validity

            Criterion-related validity is assessed when one is interested in determining the relationship of scores on a test to a specific criterion. An example is that scores on an admissions test for graduate school should be related to relevant criteria such as grade point average or completion of the program. Conversely, an instrument that measured your hat size would most assuredly demonstrate very poor criterion-related validity with respect to success in graduate school.

4.      Construct validity

Construct validity is the degree to which an instrument measures the trait or theoretical construct that it is intended to measure. For example, if one were to develop an instrument to measure intelligence that does indeed measure IQ, than this test is construct valid. Construct validity is very much an ongoing process as one refines a theory, if necessary, in order to make predictions about test scores in various settings and situations.

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REFERENCES

Allen, M. J., & Yen, W. M. (1979). Introduction to measurement theory. Monterey, CA: Brooks/Cole.

Kuder, G. F., & Richardson, M. W. (1937). The theory of the estimation of test reliability. Psychometrika, 2, 151-160.