Longitudinal studies: social and psychological factors

In spite of the great variety of longitudinal studies, one may consider two main orientations: on one hand the "comprehensive" studies, based on the combined or parallel observation of numerous psychosocial characteristics collected at successive stages of the child's development; on the other hand, studies focussed on limited topics based on the observation and longitudinal analysis of a restricted number of specific characteristics. Some examples of these different approaches are presented. The chapter considers, finally, several methodological issues, including new developments as well as constraints and problems. Recent methodological developments concern, i.a., videoscopic recording techniques which may be applied to the behaviour of mother and child (etc...) whether in the laboratory or in normal life-situations. Moreover, in view of the statistical analysis of the datas appropriate instruments are developed which at the same time keep the nuances and details of the clinical observation. Finally, some examples of problems linked to the attrition-rate of the observed sample are presented, as well as specific ethical issues raised by longitudinal studies.