Statistical analysis and reporting: common errors found during peer review and how to avoid them.

When performing statistical peer review for Swiss Medical Weekly papers there often appear to be common errors or recurring themes regarding the reporting of study designs, statistical analysis methods, results and their interpretation. In order to help authors with choosing and describing the most appropriate analysis methods and reporting their results, we have created a guide to the most common issues and how to avoid them. This guide will follow the recommended structure for original papers as provided in the guidelines for authors (http://blog.smw.ch/what-smw-has-to-offer/guidelines-for-authors/), and provide advice for each section. This paper is intended to provide an overview of statistical methods and tips for writing your paper; it is not a comprehensive review of all statistical methods. Guidance is provided about the choice of statistical methods for different situations and types of data, how to report the methods, present figures and tables, and how to correctly present and interpret the results.