Talk:Learning and Evaluation/Efficiency, effectiveness and impact
The definition of 'program efficiency' in the original version of this article relates to cost effectiveness NOT efficiency. The issue is apparent when you analyse the difference in the post between 'program efficiency' and 'program effectiveness.' The only real difference is that 'efficiency' compares effectiveness against the cost. The concept referred to as 'program efficiency' in this model comes after Effectiveness. You need to understand the effectiveness of the program before you can measure 'program efficiency.' It is, as I argued above, cost effectiveness' not efficiency.
The literature defining efficiency in such terms (e.g. Cugelman & Otero 2010) is a minority view (see for example, http://betterevaluation.org/evaluation-options/value_for_money). Efficiency relates to the energy used in processes and the minimisation of waste inherent in such processes (check any dictionary). The definition of program efficiency needs, as most such definitions do, to reflect this common understanding of efficiency or the use of the term will lead to confusion and misunderstandings. Program efficiency has nothing to do with the benefits of the activity or its effectiveness. An efficient program is one in which the cost per product or service is low relative to some other program, or relative to an ideal. Measurements of program efficiency relate to the cost in relation to products or services NOT to benefits or outcomes.
Some of the confusion arises from conflating outputs with outcomes. While some of the literature equates outputs with "measurable change towards a goal" most of the literature limits outputs to products and services. So while, program efficiency does relate to outputs, outputs are not the results of activity (outcomes). Outputs are the products and services provided by the program.
Secondly there are at least two competing definitions of impact. The definition used here for 'impact' is not inherently different from those for vision, goal, outcome etc. It make little sense to use impact for such concepts. The competing definition, and the one I prefer, relates to the consequences of the program, both intended and unintended.