Develops a statistical test for the hypothesis that alpha'(1) =alpha'(2) when alpha'(1) is the Spearman-Brown extrapolated value of Cronbach's alpha reliability for test 1 and alpha'(2) is the unadjusted coefficient for test 2. The test is shown to exercise tight control of Type I error. (Author/SLD)

Considers the degree of bias in testlet-based alpha (internal consistency reliability) through hypothetical examples and real test data from four tests of the Iowa Tests of Basic Skills. Presents a simple formula for computing a testlet-based congeneric coefficient. (SLD)

The Feldt-Gilmer congeneric reliability coefficients make it possible to estimate the reliability of a test composed of parts of unequal, unknown length. The approximate standard errors of the Feldt-Gilmer coefficients are derived via a method using the multivariate Taylor's expansion. Monte Carlo simulation is employed to corroborate the…