Two issues associated with the attrition level in a study are important for the effective evaluation of positive youth development programs. One is a programmatic challenge for investigators, and the other is an important methodological issue. First, in studying populations that are socioeconomically challenged, certain risk factors have an impact on attrition. Neighborhood risk factors such as community disorganization and mobility, as well as family risk factors of severe stress and poor family management practices, all lead to conditions which increase the likelihood of attrition. This presents a programmatic challenge for investigators who want to retain participants through follow-up. Strategies must be conceived to assure adequate subject retention, and it is important that investigators document those strategies. Assuring higher quality levels of implementation monitoring and management generally contributes to higher levels of subject retention. The majority of effective positive youth development program evaluations did an adequate attrition analysis; however, fewer addressed strategies for effective subject retention.
Second, it is essential to analyze the attrition rates that resulted during the intervention in order to understand whether different intervention group conditions or sub-groups had distinguishing characteristics which affect their presumed equivalence. This is particularly important in the case of strong quasi-experimental research designs, which rely on the ability to demonstrate that their groups were comparable. If an attrition analysis reveals significant, previously undetected differences between members of intervention and comparison groups, these differences need to be controlled for in subsequent analysis, otherwise it seriously impedes the investigators' ability to draw conclusions about the study's effects.