Appendix Figure 2. Stratification of providers.

Quality improvement organizations (QIOs) were required to recruit a limited number of nursing homes, home health agencies, and physician offices into identified participant groups (IPGs) for focused quality improvement interventions. Facilities not participating in the IPG for a given setting are labeled "non-IPG" for that setting. For a given quality measure, IPG nursing homes and home health agencies are subdivided into those focusing on a specified quality measure (IPG-select) and those not focusing on the specified measure (IPG-other). *Low-volume nursing homes and home health agencies and non–primary care physicians were not eligible for the IPG for contractual reasons.