Application of Group-Level Item Response Models in the Evaluation of Consumer Reports About Health Plan Quality.

Group-level parametric and non-parametric item response theory models were applied to the Consumer Assessment of Healthcare Providers and Systems (CAHPS(®)) 2.0 core items in a sample of 35,572 Medicaid recipients nested within 131 health plans. Results indicated that CAHPS responses are dominated by within health plan variation, and only weakly influenced by between health plan variation. Thus, although the CAHPS 2.0 survey has acceptable psychometric properties when analyzed at the individual level, large sample sizes are needed to reliably differentiate among health plans. These results illustrate why it is important to study evaluations of health care, such as CAHPS, at multiple levels of analyses.