As an alternative to Cronbach's [alpha] for estimating scale reliability, McDonald's [omega] has attracted increased attention within the methodological community for its less stringent measurement assumptions. Notwithstanding, [omega] is still seldom used by practitioners, likely due to its unavailability in popular software packages (e.g., SPSS)…

Comparisons were made among various methods of estimating the reliability of pass-fail decisions based on mastery tests. The reliability indices that are considered are p, the proportion of agreements between two estimates, and kappa, the proportion of agreements corrected for chance. Estimates of these two indices were made on the basis of…

The reliabilities of various observational measures were determined, and the influence of both the number and the length of the observation periods on reliability was examined, both separately and jointly. A single simplifying assumption leads to a variant of the Spearman-Brown formula, which may have wider application. (Author/CTM)