Program Theory of Change

The PToC and Logic Models

A PToC is most readily understood in contrast to a logic model. Even though the terms PToC and logic model are often used interchangeably, scholars in the evaluation community have begun to address the difference between the two. One of the main concerns with the conflation of these two terms is that they serve different purposes and consist of different, although often overlapping, information.

A primary distinguishing difference is that a program’s logic model focuses on the actual operation of the program and allows the evaluator to examine the implementation of the program’s components. In contrast, the PToC provides the theoretical foundations of change processes and can be used to aid the evaluator in examining the mechanisms that cause change or in answering the questions of why and how a program works.

Most notably, a PToC represents the conceptual causal model of the pathways between the program’s outcomes and activities; it also provides explanations for these hypothesized relationships, which may include indicators of change. In contrast, logic models are typically used to identify specific program components, consisting of linear descriptions of the program’s actual (as opposed to the conceptual) resources (i.e., inputs), activities, outputs, outcomes, and sometimes impacts. This depiction is often used to identify the way in which these program components fit together.

Types of PToC Models

There is no standardized model for what a PToC should include; as a result, there are no established unifying criteria for the components in a PToC. Instead, there are various ways in which a PToC can be depicted. Two prominent approaches to creating a PToC are distinguished by the level of detail included in the model.

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