Thinking small: Research designs appropriate for clinical practice

Even though some treatments have been shown to be efficacious in clinical trials, there is no guarantee that they are effective with a specific patient. This article outlines some of the methods clinicians can use to evaluate the effectiveness of therapy with individual patients. These methods include 1) the before-after design, 2) the reversal design, 3) interrupted time series, and 4) multiple baselines. This paper recommends that patients who are being treated, whether privately or in hospital, be seen as experiments with a sample size of 1 and that their progress be monitored using 1 of these methods.