Statistical power analysis
Statistical power, in the context of clinical trials, refers to the probability of detecting a therapeutic effect, if a therapeutic effect actually exists.
Statistical power analysis is used to determine the minimal number of participants needed to reach a specific statistical significance. In other words, power analysis is used to make certain a clinical trial enrolls enough participants to determine the efficacy of the therapeutic effect of the therapy being studied compare to the control. Too few participants will not produce convincing evidence for regulatory approval of a therapy. Too many participants adds unnecessary cost and time to a clinical trial.