Reliability of a psychological scale

Q. Distinguish between Temporal reliability index ( TRI) and internal consistency reliability index ( ICRI). Examine their significance for an aptitude test. 10

1 thought on “Reliability of a psychological scale”

  1. Model answer outline : Temporal reliability is also called external consistency reliability as the procedures to examine it compare data from two independent processes. It includes test – retest and parallel forms methods.
    In test – retest reliability, the ratio of (test score / retest score) should be ideally 1. But it is never found in practice as several external factors influence the performance like mood, motivation, maturation, education etc.
    Internal consistency reliability, on the other hand, is often measured by split half method without time variation as it aims at judging test structure and symmetry . After diving the test into two halves ( odd-even segregation), reliability coefficient index is calculated by using product moment correlation. Moreover, correlation of the each half with the overall test score is also calculated by using Spearman – Brown’s formula. It’s called stepped up reliability.
    For an aptitude test, both TRI and ICRI should be fairly high. Specifically, ICRI must be high.

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