Discriminant validity


Discriminant validity

Discriminant validity describes the degree to which the operationalization is not similar to (diverges from) other operationalizations that it theoretically should not be similar to.

Campbell and Fiske (1959) introduced the concept of discriminant validity within their discussion on evaluating test validity. They stressed the importance of using both discriminant and convergent validation techniques when assessing new tests. A successful evaluation of discriminant validity shows that a test of a concept is not highly correlated with other tests designed to measure theoretically different concepts.

In showing that two scales do not correlate, it is necessary to correct for attenuation in the correlation due to measurement error. It is possible to calculate the extent to which the two scales overlap by using the following formula where rxy is correlation between x and y, rxx is the reliability of x, and ryy is the reliability of y:

\cfrac{r_{xy}}{\sqrt{r_{xx} \cdot r_{yy}}}

Although there is no standard value for discriminant validity, a result less than .85 tells us that discriminant validity likely exists between the two scales. A result greater than .85, however, tells us that the two constructs overlap greatly and they are likely measuring the same thing. Therefore, we cannot claim discriminant validity between them.

Consider researchers developing a new scale designed to measure Narcissism. They may want to show discriminant validity with a scale measuring Self-esteem. Narcissism and Self-esteem are theoretically different concepts, and therefore it is important that the researchers show that their new scale measures Narcissism and not simply Self-esteem.

First, we can calculate the Average Inter-Item Correlations within and between the two scales:


Narcissism — Narcissism: 0.47
Narcissism — Self-esteem: 0.30
Self-esteem — Self-esteem: 0.52

We then use the correction for attenuation formula:

\cfrac{0.30}{\sqrt{0.47 * 0.52}} = 0.607

Since 0.607 is less than 0.85, we can conclude that discriminant validity exists between the scale measuring narcissism and the scale measuring self-esteem. The two scales measure theoretically different constructs.

See also

References

  • Campell, D. T., & Fiske, D. W. (1959). Convergent and discriminant validation by the multitrait-multimethod matrix. Psychological Bulletin, 56, 81-105.
  • John, O.P., & Benet-Martinez, V. (2000). Measurement: Reliability, construct validation, and scale construction. In H. T. Reis & C. M. Judd (Eds.), Handbook of research methods in social psychology, pp. 339-369. New York: Cambridge University Press.

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Discriminant Validity — ⇡ Validität …   Lexikon der Economics

  • Validity (statistics) — In psychology, validity has two distinct fields of application. The first involves test validity, a concept that has evolved with the field of psychometrics but which textbooks still commonly gloss over in explaining that it is the degree to… …   Wikipedia

  • Convergent validity — Convergent validity, is the degree to which an operation is similar to (converges on) other operations that it theoretically should also be similar to. For instance, to show the convergent validity of a test of mathematics skills, the scores on… …   Wikipedia

  • Construct validity — In science (e.g. social sciences and psychometrics), construct validity refers to whether a scale measures or correlates with the theorized psychological scientific construct (e.g., fluid intelligence ) that it purports to measure. In other words …   Wikipedia

  • Concurrent validity — is a parameter used in sociology, psychology, and other psychometric or behavioral sciences. Concurrent validity is demonstrated where a test correlates well with a measure that has previously been validated. The two measures may be for the same… …   Wikipedia

  • Linear discriminant analysis — (LDA) and the related Fisher s linear discriminant are methods used in statistics, pattern recognition and machine learning to find a linear combination of features which characterize or separate two or more classes of objects or events. The… …   Wikipedia

  • Multitrait-multimethod matrix — The multitrait multimethod (MTMM) matrix is an approach to examining Construct Validity developed by Campbell and Fiske(1959)[1]. There are six major considerations when examining a construct s validity through the MTMM matrix, which are as… …   Wikipedia

  • Scale (social sciences) — In the social sciences, scaling is the process of measuring or ordering entities with respect to quantitative attributes or traits. For example, a scaling technique might involve estimating individuals levels of extraversion, or the perceived… …   Wikipedia

  • Quantitative marketing research — is the application of quantitative research techniques to the field of marketing. It has roots in both the positivist view of the world, and the modern marketing viewpoint that marketing is an interactive process in which both the buyer and… …   Wikipedia

  • List of mathematics articles (D) — NOTOC D D distribution D module D D Agostino s K squared test D Alembert Euler condition D Alembert operator D Alembert s formula D Alembert s paradox D Alembert s principle Dagger category Dagger compact category Dagger symmetric monoidal… …   Wikipedia