Program Theory

themesProgram Theory or theory-based methodology involves thinking about how a project, program or policy works, including the processes, outcomes and decisions taking place, the contribution mechanisms that interact between them, and the context in which the intervention exists.

Logic Models are an important tool for helping to understand and present program theory. There is no standard template for logic models; they can be presented horizontally or vertically. The logic model stages presented below provide a basic guide, although outcomes are sometimes sub-divided into immediate, intermediate and extended categories. If using a horizontal template, it is helpful to consider the logic model as symmetrical between left and right whereby the impacts reflect the rationale (sphere of interest), the outcomes reflect the objectives (sphere of influence), and the outputs link to the inputs (sphere of control).


Theory of Change refers to the causal links or mechanisms affecting the different stages of a logic model. Also termed impact pathways or pathways of change, theory of change explains how an intervention is expected to produce its results. These causal links can be presented through a logic model, as highlighted in red below, but can also be used for outcome mapping, process mapping and systems approaches which are more complicated. In most instances, theory of change refers to if>then links, for example, if an intervention completes a certain activity, then it is expected to lead to a certain output. In this sense, the theory of change is equivalent to a hypothesis or series of hypotheses to be tested.


Attribution and Contribution refer to whether an effect has been caused by an intervention. In other words, it tests causality or the theory of change. More accurately, attribution refers to a yes or no judgment of causality, whereas contribution refers to the extent to which an effect is attributable to the intervention, usually expressed as a contribution rate.

Outcome Mapping and Process Mapping investigate in greater detail the stages in a logic model and/or the theory of change mechanisms. Whereas a logic model presents a high level summary of intervention effects, outcome mapping explores the intermediate steps, mediator variables or proximal outcomes that occur between each stage of the logic model. Similarly, process mapping looks in greater detail at an intervention’s theory of action (more detailed theory of change). The logic model below represents a very simple example of outcome and process mapping. Alternatively, visual tools like decision trees and flow charts can be used.


Systems Approaches can sometimes be more suitable than linear logic models to understand an intervention’s program theory, even as a headline summary. For example, an intervention may be too complicated to be represented as a closed system and this is one of the biggest criticisms of logic models. In reality, an intervention is likely to be one part of a larger system. For example, an output may be due to several causes outside of the intervention activity. Taking a systems approach can still involve using a logic model but mainly as a guiding framework to focus on one manageable line of enquiry and to identify extraneous factors or externalities. Alternatively, other ways of illustrating systems approaches are non-linear and more similar to mindmaps.