A Variance Components Model for Measurement Procedures Associated with a Table of Specifications

Abstract

Although many tests are developed according to a table of specifications, the literature contains little guidance to measurement specialists for considering the measurement properties of tests developed in this manner. Rather, most of the literature makes the simplistic assumption that the entire set of items are drawn from (or represent) a common undifferentiated domain or universe. This paper presents a variance components model for many measurement procedures that are associated with a table of specifications. In addition, simple procedures are provided for estimating the model parameters (variance components and category means) and functions of them (e.g., composite universe score variance and error variances).