Estimating the accuracy of psychological scales using longitudinal data

This article presents a method for estimating the accuracy of psychological screening scales using receiver operating characteristic curves and associated statistics.Screening scales are typically semicontinuous within a known range with distributions that are nearly symmetric when the target condition is present and highly skewed when the condition is absent.We model screening scale outcomes using truncated normal distributions that accommodate these different distributional shapes and use subject.specific random effects to adjust for multiple assessments within individuals.Using the proposed model, we estimate the accuracy of the Symptom Checklist as a measure of major depression from a repeatedly screened sample of patients.