The reliability of residual scores created in the analysis of covariance in pretest-posttest designs, adjusted for a singe covariate, is compared with that of simple difference scores as relevant parameters vary. Little gain in reliability is created by analysis of covariance, which also suffers from reliability problems. (SLD)

Regression to the mean (RTM) is often misunderstood. It is demonstrated that artifactual RTM depends fundamentally on the magnitude of measurement error at pretest. Adjustment usually involves estimating the measurement error and determining consequences, but even without adjustment, effects of RTM can be ameliorated. (SLD)

Statistical methodologists have sometimes criticized the use of conventional statistics in meta-analysis, and in recent years a number of them have advocated the use of a special new statistical methodology for research synthesis. An examination of recent books describing this methodology shows that it is seriously limited in its applicability to…

The regression-discontinuity design involving a treatment interaction effect (TIE), pretest-posttest functional form specification, and choice of point-of-estimation of the TIE are examined. Formulas for controlling the magnitude of TIE in simulations can be used for simulating the randomized experimental case where estimation is not at the…

Viewing the reliability for criterion-referenced tests as that of mastery classification decisions, three models for determining reliability were examined using two test administrations so that two estimates could be compared to a standard. A major purpose of the research was to determine how several reliability coefficients (coefficient kappa, an…

A conceptual approach and a set of computer simulations are presented to demonstrate that random measurement error in the pretest does not bias the estimate of the treatment effect in the regression-discontinuity design. Focus is on the case of no interaction between pretest and treatment on posttest. (SLD)