Balanced incomplete block design: description, case study, and implications for practice.

This article discusses the use of balanced incomplete block design for process evaluation and presents a case study of its use. This technique produces a weighted ranking of program elements, showing the relative importance of each element and allowing comparison of process and content elements. The article presents a case study in which the technique was used to evaluate the Chronic Disease Self-Management Program. Participants and lay course leaders were asked to rank 13 course elements for their helpfulness. The most valued element, sharing or unstructured interactions among participants, was not an explicitly planned part of the intervention. Some of the elements least valued (nutrition, use of community resources, and medication use) are elements most emphasized by the health care system and by patient education. We found that balanced incomplete block design was easy to administer and tally. The results could be readily applied to program redesign and to needs assessment.