The distinction between two models of reliability is clarified. Reliability may be conceived of and estimated from a true score model or from the perspective of sampling precision. Basic models are developed and illustrated for each approach using data from the author's work on measuring organizational climate. (SLD)

In this paper, performance assessments are cast within a sampling framework. A performance assessment score is viewed as a sample of student performance drawn from a complex universe defined by a combination of all possible tasks, occasions, raters, and measurement methods. Using generalizability theory, the authors present evidence bearing on the…