This subject examines public health in its role in health services today. Philosophically and traditionally, public health relates to applying the medical model of health care by identifying the distributions and determinants of disease, and from this knowledge policies are developed which provide management frameworks within communities. Epidemiology is evidence-based research concerned with studying groups of people to establish causal relationships, the rates and ratios associated with disease development and the identification of at-risk populations. This provides a framework for the clinical decision-making process which has developed as a central component of current public health practices.