Scientists, policymakers, and advocates are increasingly advised to use "the public health approach" to address myriad social issues, from alcoholism and arthritis to vision care and war. However, it is rarely clear what exactly is meant by "the public health approach." Policymakers at the Centers for Disease Control and Prevention (CDC) describe the public health approach as a four-step model: Define the problem, identify risk and protective factors, develop and test... (GunPolicy.org)