ERIC Number: EJ723305
Record Type: Journal
Publication Date: 2006
Reference Count: 27
Reliability of Total Test Scores When Considered as Ordinal Measurements
Biswas, Ajoy Kumar
Applied Psychological Measurement, v30 n1 p43-55 2006
This article studies the ordinal reliability of (total) test scores. This study is based on a classical-type linear model of observed score (X), true score (T), and random error (E). Based on the idea of Kendall's tau-a coefficient, a measure of ordinal reliability for small-examinee populations is developed. This measure is extended to large (theoretically, infinite) examinee populations. This extended measure is identified as the population version of Kendall's tau-a. Appropriateness of the traditional product moment correlation-based measures, [TX] and .XX0, is reviewed. It is observed that [TX] and .XX0 are appropriate within the family of normal distributions of (T, E) but are inappropriate in the family of nonnormal distributions. A simulated data example is considered to show that the traditional product moment correlation-based measures may be misleading. Furthermore, practical procedures are suggested for estimating ordinal reliability. Real test score data are used for demonstration.
Descriptors: True Scores, Test Theory, Test Reliability, Scores, Correlation, Measures (Individuals), Measurement Techniques
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Publication Type: Journal Articles; Reports - Evaluative
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