Note on calculating the standard error of measurement and reliability coefficients with the test-scoring machine

Abstract

Since the International test-scoring machine can yield in a single reading the difference between the scores on the odd and even items on a test, the standard deviation of the difference between these scores can easily be computed. From this constant the reliability coefficient can be obtained by the formula[Equation omitted]where ς D 2 is the variance of the difference scores and ς w 2 is the variance of the ordinary test scores including both odds and evens. (PsycInfo Database Record (c) 2025 APA, all rights reserved)