Parallel Forms Reliability

Parallel forms reliability, also known as alternate forms reliability, involves the administration of two parallel forms of the same test to a group of individuals. The two forms should be equivalent in terms of content, difficulty, and measurement (Crocker & Algina, 1986). After both forms are administered, the scores obtained on the two forms are correlated. High correlations suggest that both forms are reliable measures of the same construct.

Parallel forms reliability is particularly useful when there is a need to minimize the practice or memory effects associated with repeated administration of the same test. It is often employed in educational assessments, clinical testing, or any context where repeated testing with the same set of items is impractical or likely to lead to biased results.

For example, in educational assessment, two equivalent forms of a math test may be administered to students to reduce the influence of memory or practice on the results. By correlating the scores obtained on both forms, researchers can determine whether the two forms are consistent in measuring the same mathematical ability.