Effects of Test Length and Sample Size on the Estimates of Precision of Latent Ability Scores.

摘要

One of the most important advantages that accrue from the application of latent trait models is the possibility of specifying a target information curve and then selecting items from an item pool to produce a test with the features characterized by this curve. By proceeding in this manner, it is possible to develop a test that provides a pre-specified level of precision (Standard Error of Ability Estimate) at selected ability levels. One problem with this paradigm is that little is known about the precision of the standard error of ability estimates (SEE) under varying circumstances. The purpose of the research reported in this paper was to address three practical questions of importance and interest to test developers: 1) What are the effects of examinee sample size and test length on the precision of SEE Curves, 2) What effects do the statistical characteristics of an item pool have on the precision of SEE Curves, and 3) What is the relationship between test length and SEE Curves in typical item pools. Keywords: Latent trait theory, Psychological tests, Aptitude tests, Mathematical models. (SDW)