Population health is a strategy that uses data to study public and community health, then adjust the delivery and availability of medical and welfare services to ensure optimal results. Population health consists of three categories: health outcomes, patterns of determinants, and policies. Health outcomes focus on the effectiveness of treatments. Patterns of determinants involve searching for information on factors that can affect outcomes and predict problems. For example, if one area has an unusually high number of smokers, local hospitals can reasonably expect to see more patients with lung cancer. Policies consider the best way to deliver services within a group.