title: Simulation-Extrapolation with Latent Heteroskedastic Error Variance.
abstract: This article considers the application of the simulation-extrapolation (SIMEX) method for measurement error correction when the error variance is a function of the latent variable being measured. Heteroskedasticity of this form arises in educational and psychological applications with ability estimates from item response theory models. We conclude that there is no simple solution for applying SIMEX that generally will yield consistent estimators in this setting. However, we demonstrate that several approximate SIMEX methods can provide useful estimators, leading to recommendations for analysts dealing with this form of error in settings where SIMEX may be the most practical option.
authors.affiliation: Educational Testing Service, Princeton, NJ, USA. jrlockwood@ets.org.
authors.forename: J R
authors.initials: JR
authors.lastname: Lockwood
authors.affiliation: Educational Testing Service, Princeton, NJ, USA.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: McCaffrey
keywords: achievement test scores; covariate adjustment; item response theory; measurement error; nonlinear models