Minimizing attrition in longitudinal studies of special populations: An integrated management approach

Whilst statistical techniques are available to estimate effects for missing subjects in longitudinal designs, minimizing subject attrition is a major goal in longitudinal research. This may be particularly difficult when attempting to follow individuals who have special characteristics or disabilities. The Colorado Treatment Outcome Study, a longitudinal study of individuals with serious and persistent mental illness (SPMI), developed an integrated management approach that resulted in average re-contact rates of 95% in each follow-up year. This integrated management approach emphasized the partnership of all key parties to the research, including the community, the respondents, the field interviewers, and management. Guided by a set of values that emphasized respect for the respondent, confidentiality and community relationships, procedures were developed that included an information system, office protocols, staff selection, supervision, staff training, and subject location and engagement techniques. While each element is explicated with attention to special populations, it is their coordination and integration that is critical for success.