[Common biostatistical errors in clinical studies]

Roughly half to two third of all published biomedical studies that use statistical methods contain unacceptable errors. The present article points at common errors that may be avoided without requiring profound statistical knowledge. These errors mainly concern the minimal number of patients and sample size (statistical power), agreement between aim and conclusion, distribution of data as well as description of location and variability of data. An analysis of 150 papers in the New England Journal of Medicine and in Circulation demonstrates that these errors can also commonly be found in respected journals after statistical peer review. Editors of biomedical journals could reduce the problem by means of statistical guidelines.