Problems in designing and carrying out longitudinal research

Abstract

There is a growing realization that many of the issues of interest to clinicians concerned with problems in childhood require investigations using longitudinal research designs. The paper identifies the strengths and weaknesses of longitudinal research and guides the clinical researcher in the selection of an appropriate research design. Issues related to the design of longitudinal studies are discussed, including identifying a sample for longitudinal study, sample size considerations, and the measurement of change, including the consequences of repeated measurement. Practical problems with the conduct of longitudinal studies are covered, such as maintaining subject compliance, tracing subjects, and staff morale. The topic of the analysis of longitudinal data is the subject of a second paper.