Lipsey & Cordray（2000）は，プログラム評価の目的を下記のとおりとしている：

We take the view that the overarching goal of the program evaluation enterprise is to contribute to the improvement of social conditions by providing scientifically credible information and balanced judgement to legitimate social agents about the effectiveness of interventions intended to produce social benefits (p. 346).

さらに，評価者の役割の経時的変化を下記のとおりとしている：

In early conceptions of evaluation, evaluators were characterized as “methodological servants to the experimenting society” (Campbell, 1971), a role largely confined to assessing the effectiveness of programs devised and organized by others. Since then, the evaluator’s role has expanded so that it often includes preintervention issues, such as program design and planning, and program implementation and refinement. Thus, evaluation specialists have increasingly infiltrated the organizational development processes (Lipsey & Cordray, 2000, p. 361).

Lipsey, M., & Ｃordray, D. (2000). Evaluation methods for social intervention. Annual Review of Psychology, 51, 345-375.