Logic Models

Historical Roots

The connection between the clear and defensible articulation of the underlying logic of a program on the one hand and the development of well-targeted and contextually relevant evaluation priorities has a relatively long history within the contemporary development of the field of evaluation. As early as 1980, Joseph Wholey, who worked in an evaluation capacity for the U.S. federal government, developed the concept of evaluability assessment. Using the lenses of market analysis, an evaluability assessment yields a judgment of a program’s readiness to benefit from an evaluation. Readiness is enhanced when (a) program goals and priority information needs are well-defined, (b) program goals are clearly articulated and attainable, (c) relevant performance data can be collected at reasonable cost, and (d) intended users of the evaluation results have agreed how they will use this information. Absent these conditions, evaluation results are not likely to be useful or used.

With some prescience, more than a decade earlier, Daniel Stufflebeam developed a CIPP (Context, Input, Process, Product) framework for evaluating many federal programs that did not meet the requirements for randomized experimental evaluations. A formative CIPP evaluation was designed to provide guidance for program development, based on contextual and conceptual analyses. A summative CIPP evaluation intended to compare data on program design, implementation, and outcomes to known participant needs and to accomplishments of results for critical competitors. Stufflebeam’s CIPP thinking importantly contributed to the later development and widespread popularity of the logic model as a framework useful for both program planning and program evaluation.

In the 1980s and 1990s, another construct in the logic model family appeared in the work of evaluation scholars Carol Weiss and Huey-Tsyh Chen. This is the construct of program theory. A program theory articulates the causal change model that underlies a social or educational program and that is specifically designed to redirect or refocus behaviors or encourage movement in a new direction by the intended participants. A logic model is a descriptive account of the planned building blocks of change. A program theory is an explanatory account of the intended change process. The Aspen Roundtable for Community Change popularized the program theory construct and extended it to practitioners by promoting a theory of change approach in their early 2000s community development initiatives. The theory of change construct quickly spread to multiple sectors around the globe.

...