Читать книгу Health Psychology - Michael Murray - Страница 135

The term ‘observational study’ is used to describe research carried out to evaluate the effect of an intervention or treatment that does not have the advantages of a control group. A single group of patients is observed at various points before, during and after the treatment in an attempt to ascertain the changes that occur as a result of the treatment. There are strict limitations on the conclusions that can be reached as a consequence of the lack of a control group (e.g., see Randomized controlled trials below). However, there are occasions when a randomized controlled trial is impossible to carry out because of ethical or operational difficulties.