Validity (accuracy) is the degree to which a test or an instrument measures what it purports to measure (Nachmias & Nachmias, 1996). While there are various types of validity, this guide briefly describes only two types, namely face validity and content validity:
- Face validity: Face validity is an estimate of whether a test appears to measure a certain criterion; it does not guarantee that the test actually measures phenomena in that domain. Face validity relates to whether a test appears to be a good measure or not.
- Content validity: Unlike face validity, content validity involves “the systematic examination of the test content to determine whether it covers a representative sample of the behavior domain to be measured” (Anastasi & Urbina, 1997, p. 114 ). A test has content validity built into it by careful selection of which items to include when developing it. In order to test content validity in a test or an instrument, panel of experts are used to review the test specifications and the selection of items (Foxcroft, Paterson, le Roux & Herbst (2004, p. 49). Based on the experts’ review, the content validity of the test or an instrument is improved.
Example
To check the content validity, the instruments were given to two research supervisors. Two other independent experts in education research from the Catholic University of Eastern Africa were given the instruments to validate. They checked on the instruments’ content coverage based on the study parameters. The instruments were also given to peers for further review to determine the internal consistency. Based on the experts’ comments, the researcher made improvement on the instruments.
References
Anastasi, A., & Urbina, S. (1997). Psychological testing (7th ed). Upper Saddle River, NJ: Prentice Hall.
Foxcroft, C., Paterson, H., le Roux, N., & Herbst, D. (2004). The test use patterns and needs of psychological assessment practitioners. Human Sciences Research Council. Retrieved from http://www.hsrc.ac.za
Nachmias, D., & Nachmias, C. (1996). Research Methods in the Social Sciences (5th Ed.,) New York: St. Martins Press.