What are the five components of a logic model in health program planning, and how do they relate to each other?

The five components are resources (inputs), activities, outputs, outcomes, and impact. The model reads from left to right like a chain of reasoning: the first two components are the planned work, and the last three are the intended results. Resources and activities combine to produce outputs, which lead to outcomes and eventually to the program's long-term impact.

According to the text, a logic model moves logically from planned work to intended results in five steps. First, resources or inputs are the items needed and available for the program, including human, financial, equipment, institutional, and community resources. Second, activities are the processes that produce the program intervention, such as health education or using tools and technology. These first two components constitute the planned work. The remaining three components constitute the intended results. Third, outputs are the direct products of the activities, such as a completed class or immunization service; successful output occurs when the intended outcome is achieved. Fourth, outcomes are the intended results or benefits that the team plans to measure, including changes in knowledge, skills, behavior, or attitude; short-term and medium-term outcomes reflect program objectives. Fifth, impact is the program goal that produces long-term community change, often occurring only after several years, even after funding ends. The model is read left to right, and at the planning stage it can also be read right to left, starting with the hoped-for impact and working backward to determine objectives, activities, outputs, and needed resources. Assumptions and external factors can be added to help clarify the theory behind the model.