A strong research design makes the evaluation evidence believable or trustworthy. A weak design makes it difficult to determine whether changes in outcomes are due to the program itself or to other factors. When possible, use a strong research design such as a randomized controlled trial or a quasi-experimental design.
A main benefit of these two designs is that participants who receive the intervention are compared with a group that do not receive the intervention, though the second group may receive standard care or treatment, sometimes known as “business as usual” or “treatment as usual.” This second group is known as the control group or the comparison group.
Here are some additional sources that provide more comprehensive information on evaluation designs:
- The Online Evaluation Resource Library provides a large collection of plans, reports, and instruments from past and current evaluations that have proven sound and representative of current evaluation practices; guidelines for improving evaluation design and practice; and a discussion forum for stimulating ongoing dialog in the evaluation community.
- The Web Center for Social Research Methods is designed for people engaged in applied social research and evaluation. The Knowledge Base is an online hypertext textbook that covers the entire research process, including formulating research questions, sampling, measurement, research design, data analysis, and reporting.