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

Dababnah et al. (2025) checked if the Personal Opportunities Scale gives the same scores for adults with IDD at two time points. They used data from the adults who answered the same 24-item survey one year apart. The team ran a measurement-invariance test to see if the scale drifted over time.

The scale held partial invariance. Factor loadings stayed steady, but three item intercepts shifted. That means a raw score of 20 at Time-1 is not the same as 20 at Time-2. Longitudinal comparisons need statistical correction or you risk seeing fake change.

Kildahl et al. (2025) found a similar story with the Aberrant Behavior Checklist. Four of five subscales stayed invariant, but the hyperactivity/non-compliance subscale drifted. Both papers warn that even trusted scales can slip over time in ID samples.

Horovitz et al. (2011) tracked psychiatric symptoms for one year in adults with severe ID. They saw stable scores except on the PDD/Autism subscale. Their finding lines up with Sarah et al.: most items hold, but a few move, so check each subscale before you claim change.

Embregts (2000) showed the Child Behavior Checklist has poor reliability (κ = 0.27–0.52) for youth with mild ID. Sarah et al. extend that worry into adulthood and add a fix: run invariance tests instead of just reliability checks.

If you use the Personal Opportunities Scale for goal setting or funding reports, rerun the invariance model yearly. When intercepts shift, convert raw scores to latent means before you tell families or payers that progress rose or fell. One extra analysis saves you from mislabeling real growth as none, or none as growth.