A logic model is a tool for enhancing program performance. It is not an end in itself. Thus, the purpose for which the logic model is to be used dictates the level of detail employed and the information included.
The Type of Program or Initiative You are Diagramming and its Complexity
A logic model of a focused, small program will obviously be less complex than a logic model representing a large, comprehensive initiative. To characterize the latter, multiple logic models may be necessary. Level of detail is often confined by what can be realistically and understandably expressed on a single page.
The Purpose of the Logic Model
For program planning (more in Section 5):
When designing a program, the logic model is often very detailed. We want to identify every element, show all the connections, list all the assumptions and factors in the external environment likely to interact. This helps identify potential gaps in logic, areas that need further exploration, externalities and risks that may be associated with the proposed action so that we can put contingency plans in place. It helps us determine resource needs and the likelihood of success. Some practitioners reverse the order of inputs-outputs-outcomes for program planning to emphasize outcomes as the beginning point for planning.
For program evaluation (more in Section 7):
The logic model has been widely used by program evaluators. The look and level of detail differs widely dependent upon evaluator training and evaluation purpose and design. Community-based practitioners who need to measure outcomes, may wish to show greater detail in the outcome chain and streamline the input and output components to the main ingredients.
These may be the most simplified and streamlined logic models. The purpose is to communicate clearly and easily with our external stakeholders. We want to avoid jargon and confusion. Typically, logic models constructed for external communications depict the key elements and show the principal linkages leading from investments to results.
Usually a very detailed logic model is used for program management purposes. In order to achieve the level of detail needed, multiple logic models may be used that depict different sequences or aspects of the overall program.
The Agency Orientation
Many agencies have developed their own variation of a logic model to reflect their particular needs and orientation.