Different Trial Designs
In the standard trial design a subject or patient is considered suitable for entry to the trial and is then randomized to a treatment group; each group receives a single treatment. A fixed number of persons enter the trial and are followed for a predetermined interval of time; treatment is stopped at the end of this period. Other trial designs have to be considered. The subject may be asked to take more than one treatment consecutively (cross-over trial), more than one treatment simultaneously (trial to detect an interaction between treatments), or more than one treatment consecutively and concurrently (cross-over trial to detect an interaction). The remaining design variations do not involve a fixed number of persons being entered. The standard trial, cross-over trial, trial to detect an interaction between treatments, and cross-over trial to detect an interaction are illustrated in figure 11-1 for four treatments A, B, C, and D.
KeywordsPlacebo Sugar Arthritis Heroin Cough
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