Estimating Reliability for Tests With One Constructed‐Response Item in a Section

Abstract

The goal of this paper is to find better ways to estimate the internal consistency reliability of scores on tests with a specific type of design that are often encountered in practice: tests with constructed‐response items clustered into sections that are not parallel or tau‐equivalent, and one of the sections has only one item. To estimate the reliability of scores on this kind of test, we propose a two‐step approach (denoted as CA_STR) that first estimates the reliability of scores on the section with a single item using the correction for attenuation method and then estimates the reliability of scores on the whole test using the stratified coefficient alpha. We compared the CA_STR method with three other reliability estimation approaches under various conditions using both real and simulated data. We found that overall, the CA_STR method performed the best and it was easy to implement.