GUEST EDITORIAL Twenty Statistical Errors Even YOU Can Find in Biomedical Research Articles

“Critical reviewers of the biomedical literature have consistently found that about half the articles that used statistical methods did so incorrectly.” (1) “Good research deserves to be presented well, and good presentation is as much a part of the research as the collection and analysis of the data. We recognize good writing when we see it; let us also recognize that science has the right to be written well.” (2) Statistical probability was first discussed in the medical literature in the 1930s (3). Since then, researchers in several fields of medicine have found high rates of statistical errors in large numbers of scientific articles, even in the best journals (4-7). The problem of poor statistical reporting is, in fact, longstanding, widespread, potentially serious, and not well known, despite the fact that most errors concern basic statistical concepts and can be easily avoided by following a few guidelines (8). The problem of poor statistical reporting has received more attention with the growth of the evidence-based medicine movement. Evidence-based medicine is literature-based medicine and depends on the quality of published research. As a result, several groups have proposed reporting guidelines for different types of trials (9-11), and a comprehensive set of guidelines for reporting statistics in medicine has been compiled from an extensive review of the literature (12). Here, I describe 20 common statistical reporting guidelines that can be followed by authors, editors, and reviewers who know little about statistical analysis. These guidelines are but the tip of the iceberg: readers wanting to know more about the iceberg should consult more detailed texts (12), as well as the references cited here. To keep the tension mounting in an often dull subject, the guidelines are presented in order of increasing importance. Error #1: Reporting measurements with unnecessary precision