Advantages and limits of longitudinal evaluation research in energy conservation

Abstract

Evaluations of conservation programs tend to be single snap-shots of program effects, usually taken soon after a program begins. The resulting picture may miss the delayed effects of the program, or it may overestimate the long-term impacts. The evaluation described in this paper follows the research cohorts for 4 years, and, as a case study, it provides ideas on both advantages and limitations to a longitudinal approach. Suggestions are offered for improving the usefulness of this type of program evaluation.