Concept inventories (CIs)--typically multiple-choice instruments that focus on a single or small subset of closely related topics--have been used in science education for more than a decade. This paper describes the development and validation of a new CI for astronomy, the "Star Properties Concept Inventory" (SPCI). Questions cover the areas of…

The goal of test design is to devise an instrument that will provide a stable and accurate assessment of student ability in some area. One means of reaching this goal is through the use of latent trait models, which determine the relationship between the unobservable trait or ability and the observable test performance. Three common latent trait…