Epilogue: a critical look at a nascent field.

A broad coalition of partners, entitled PHIRIC (Population Health Intervention Research Initiative for Canada), are working to increase the amount/quality of population health intervention research (PHIR) in our country. A central theme is to advance the science in this area. The current CJPH Supplement is welcomed as a set of diverse studies done to further our understanding of PHIR. The papers illustrate the range of questions that can be addressed and the variety of methods that need to be utilized. There is a need for critical reflection on three questions: 1) what constitutes PHIR? 2) which intervention parameters can be researched? and 3) what methods are recognized by the research community? Although legitimate attempts to define PHIR exist, the boundaries remain elusive. (Even the choice of articles in the current Supplement might be questioned.) It has cogently been argued that 'true' public health interventions intend to change risk conditions and alter distributions of health risk. This commentary suggests an important amendment to prior evaluation questions in stating that PHIR must pay attention to how intervention outcomes are distributed. There are also questions inherent in assessing the equity and distribution of an outcome. The bottom line is that we need to spread the word: more research is needed.