Distinction between types of evaluation - formative, process & impact

Posted by Paul / on 08/25/2009 / 0 Comments


Hi, I have been writing some material recently, some of which came out of the experience of being at the YEN Evaluation Clinic. I will put up some postings here in the YEN networking site which refers to it and leads through it in a systematic sequence. This first posting refers to two articles about types of evaluation.  The YEN Evaluation Clinic tended to focus on impact evaluation - which is a current major focus in international development. Impact evaluation is a great idea when you can do it. But before we just jump right into planning impact evaluations, it is important to be clear about the types of evaluation which are available if we are to take what I call a strategic approach to evaluation. These evaluation types are not really alternatives to each other as they are trying to do different things. But is is a matter of working out what the best mix of them is for any particular project.

There are three major types of evaluation. Types is defined here as classifying evaluation on the basis of the purpose for which one is doing the evaluation activity.

There are three types of evaluation:

  • Impact/outcome evaluation - attempts to attribute intended and unintended positive and negative high-level outcomes to a particular intervention.
  • Process evaluation - attempts to describe the course and/or context of an intervention.
  • Formative/developmental evaluation - attempts to optimize program implementation using evaluation methods.

These three types of evaluation are interrelated. For instance, findings from process evaluation can be used as input into formative evaluation if the program is still running and is open to amendment. Process evaluation can be used to help interpret impact/outcome evaluation findings and impact/outcome evaluations of pilot/demonstration programs can be used as input into formative evaluation. The diagram at the top of the page (to look at it, just click on it) shows how you can think about applying these different types of evaluation at different points in the program life-cycle.

When we approach planning for an evaluation, taking a strategic approach means that we are aware that we have these three types of evaluation as possibilities and do not assume that we will be able to use any one of them before we have assessed the appropriatness, feasibility and affordability of each of these types of evaluation in regard to any project.

In addition to the types of evaluation based on the purpose of the evaluation - there are other aspects of evaluation which have different terms assigned to them. There are approaches - these are broad, sometimes philosophically orientated, statements about the way one should go about evaluation; there are evaluation methods, which are the specific information collection methods one uses; there are evaluation information analysis techniques, which are the techniques for analyzing data; and there are evaluation designs, which are the way in which you put all of the other ingredients (approaches, types, methods and analysis techniques) together.

The papers are below. Check them out and make and comments you have at the bottom of them.

Duignan, P. (2009). Terminology in evaluation: Approaches, types (purposes), methods, analysis techniques and designs. Outcomes Theory Knowledge Base Article No. 259. (http://knol.google.com/k/paul-duignan-phd/terminology-in-evaluation-approaches/2m7zd68aaz774/120).


Duignan, P. (2009). Evaluation types: Formative/developmental, process, impact/outcome evaluation. Outcomes Theory Knowledge Base Article No. 256. (http://knol.google.com/k/paul-duignan-phd/-/2m7zd68aaz774/119).


Paul Duignan, PhD

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