Science and scientists have played an important role in the field of policymaking, informing and guiding decisions on a wide range of issues, including health care, land management, pollution, transportation and even social issues. While it is rare that scientific evidence is the only consideration in a policy decision—beliefs, experience, trial and error, and personal or political values are also used in making policy decisions—science is on balance a more dependable and defensible guide than informed hunches, analogies or personal experience.