What is population health?

Population health is a relatively new term that has not yet been precisely defined. Is it a concept of health or a field of study of health determinants? We propose that the definition be the health outcomes of a group of individuals, including the distribution of such outcomes within the group, and we argue that the field of population health includes health outcomes, patterns of health determinants, and policies and interventions that link these two. We present a rationale for this definition and note its differentiation from public health, health promotion, and social epidemiology. We invite critiques and discussion that may lead to some consensus on this emerging concept.