Lord's paradox arises from the conflicting inferences obtained from two alternative approaches that are typically used in evaluating the treatment effect using a pre-post test design. The two main approaches for analyzing such data are: (1) to regress the change from pretest to posttest on the treatment indicator (change score approach; CS); (2)…

There is a degree of instability in any measurement, so that if it is repeated, it is possible that a different result may be obtained. Such instability, generally described as "measurement error", may affect the conclusions drawn from an investigation, and methods exist for allowing it. It is less widely known that different disciplines, and…

When a test is made to separate a group into two distinct subgroups, as well as to provide an estimate of the mean performance of one subgroup (or both of them), such estimates will be biased due to the unreliability of the test. Suggestions for corrective procedures are presented. (RL)

A logistic model was used to generate data to serve as a proxy for an immediate retest from item responses to a fourth grade standardized reading comprehension test of 45 items. Assuming that the actual test may be considered a pretest and the proxy data may be considered a retest, the effect of regression was investigated using a percentage of…

Covariance structure modelling is applied to the problem of estimating reliability and measurement error in survey data. To provide a basis for grouping certain question or variable types (data from questions), a simple typology based on the formal characteristics of the questions is outlined. From this classification, models for the different…

Classification studies are important for practitioners who need to identify individuals for specialized treatment or intervention. When interventions are irreversible or misclassifications are costly, information about the proficiency of different classification procedures becomes invaluable. This study furnishes information about the relative…

The regression-discontinuity approach to evaluating educational programs is reviewed, and regression-discontinuity post-program mean differences under various conditions are discussed. The regression-discontinuity design is used to determine whether post-program differences exist between an experimental program and a control group. The difference…