Habicht J P, Victora C G, Vaughan J P
Division of Nutritional Sciences, Cornell University, USA.
Int J Epidemiol. 1999 Feb;28(1):10-8. doi: 10.1093/ije/28.1.10.
The question of why to evaluate a programme is seldom discussed in the literature. The present paper argues that the answer to this question is essential for choosing an appropriate evaluation design. The discussion is centered on summative evaluations of large-scale programme effectiveness, drawing upon examples from the fields of health and nutrition but the findings may be applicable to other subject areas. The main objective of an evaluation is to influence decisions. How complex and precise the evaluation must be depends on who the decision maker is and on what types of decisions will be taken as a consequence of the findings. Different decision makers demand not only different types of information but also vary in their requirements of how informative and precise the findings must be. Both complex and simple evaluations, however, should be equally rigorous in relating the design to the decisions. Based on the types of decisions that may be taken, a framework is proposed for deciding upon appropriate evaluation designs. Its first axis concerns the indicators of interest, whether these refer to provision or utilization of services, coverage or impact measures. The second axis refers to the type of inference to be made, whether this is a statement of adequacy, plausibility or probability. In addition to the above framework, other factors affect the choice of an evaluation design, including the efficacy of the intervention, the field of knowledge, timing and costs. Regarding the latter, decision makers should be made aware that evaluation costs increase rapidly with complexity so that often a compromise must be reached. Examples are given of how to use the two classification axes, as well as these additional factors, for helping decision makers and evaluators translate the need for evaluation--the why--into the appropriate design--the how.
为何要对一个项目进行评估，这一问题在文献中鲜少被讨论。本文认为，这个问题的答案对于选择合适的评估设计至关重要。讨论聚焦于大规模项目成效的总结性评估，借鉴了健康与营养领域的实例，但研究结果可能适用于其他学科领域。评估的主要目标是影响决策。评估必须有多复杂和精确，取决于决策者是谁以及根据评估结果将做出何种类型的决策。不同的决策者不仅需要不同类型的信息，而且对评估结果的信息量和精确程度的要求也各不相同。然而，无论是复杂的评估还是简单的评估，在将设计与决策联系起来时都应同样严谨。基于可能做出的决策类型，本文提出了一个用于确定合适评估设计的框架。其第一个轴涉及感兴趣的指标，这些指标是指服务的提供或利用、覆盖范围还是影响措施。第二个轴指的是要进行的推理类型，即这是关于充分性、合理性还是可能性的陈述。除上述框架外，其他因素也会影响评估设计的选择，包括干预措施的效果、知识领域、时间安排和成本。关于成本，应让决策者意识到，评估成本会随着复杂性迅速增加，因此往往必须达成妥协。文中给出了如何使用这两个分类轴以及这些额外因素，来帮助决策者和评估人员将评估的需求——即为何评估——转化为合适的设计——即如何评估。
