Читать книгу The Pocket Guide to Critical Appraisal - Iain K. Crombie - Страница 28

The essential feature of this design is that the treatment patients receive is selected by the doctors who are responsible for their care, based on an assessment of their specific clinical circumstances. Rather than being randomised to treatment groups, clinical judgement is used to decide which treatment will be best for each patient. As a result, the patients given one treatment may differ systematically from those given the other treatment. This is the major weakness of the research design, as the two groups of patients will be different at the start of the study (i.e. before they receive their treatment).