Clinicians' Guide to Statistics for Medical Practice and Research: Part II.

In the last issue of the The Ochsner Journal, Part I of this series provided basic statistical principles for the practicing clinician to use in the review of the medical literature and in conducting clinical research. We included discussion of formulating the study question and study goals, choosing the appropriate study design, and using the appropriate statistical test (1). In this issue, we present the final part of the two-part series and will describe key issues relevant to statistical significance, statistical power, error, bias and confounding, and clinical relevance of study results. As with Part I, this is not intended to be a comprehensive review of statistical principles, but rather a quick reference for practical application of statistical principles. Are the Results of the Study Significant? The Role of Chance