Evaluating Measurement Invariance Over Time for a Personal Opportunities Scale for People With IDD: Implications for Policy and Practice.

Personal opportunities refer to chances for people with intellectual and developmental disabilities (IDD) to take self-directed action based on their interests, strengths, and preferences. This study tested for measurement invariance across five years of cross-sectional data, including data collected during the COVID-19 pandemic, to determine whether the scale performed consistently over time. Analysis revealed significant differences in both the National Core Indicators In-Person Survey (NCI-IPS) outcomes and in the Personal Opportunities scale. Measurement invariance testing indicated partial threshold and loading invariance, but not intercept invariance, suggesting that the ways in which participants perceived or responded to scale items changed over time. We recommend that researchers utilizing scaled measures with longitudinal outcomes employ statistical checks, including measurement invariance, to ensure the scale performs consistently over time.