Читать книгу Health Psychology - Michael Murray - Страница 131

Longitudinal designs involve measuring responses of a single sample on more than one occasion. The measurements may be prospective or retrospective. Prospective longitudinal designs allow greater control over the sample, the variables measured and the times when the measurements take place. Such designs are superior to cross-sectional designs because one is better able to investigate hypotheses of causation when the associations between variables are measured over time. Longitudinal designs are among the most powerful designs available for the evaluation of treatments and of theories about human experience and behaviour, but they are also the most expensive in terms of labour, time and money.