Testing programs often rely on common-item equating to maintain a single measurement scale across multiple test administrations and multiple years. Changes over time, in the item parameters and the latent trait underlying the scale, can lead to inaccurate score comparisons and misclassifications of examinees. This study examined how instability in…

The problem of factor score indeterminacy implies that the factor and the error scores cannot be completely disentangled in the factor model. It is therefore proposed to compute Harman's factor score predictor that contains an additive combination of factor and error variance. This additive combination is discussed in the framework of classical…

Equations for estimating the value of the multiple correlation coefficient in the population underlying a sample and the value of the population validity coefficient of a sample regression equation were investigated. Results indicated that cross-validation may no longer be necessary for certain purposes. (Author/MH)