The purpose of this study is to evaluate the effectiveness of state agencies current peer group systems, and to provide guidance to state agencies on how to evaluate and update their systems. Specifically, it uses empirical analysis to identify one or more effective models for establishing vendor peer groups that could apply to most state agencies.

The purpose of the study was to learn the extent to which retail grocers, defined as "vendors" in the WIC Program, authorized to provide food to WIC participants, were violating program rules and procedures, and to determine which programmatic and/or demographic variables could be associated with vendor violations.