Choosing statistical tests: part 12 of a series on evaluation of scientific publications.

BACKGROUND The interpretation of scientific articles often requires an understanding of the methods of inferential statistics. This article informs the reader about frequently used statistical tests and their correct application. METHODS The most commonly used statistical tests were identified through a selective literature search on the methodology of medical research publications. These tests are discussed in this article, along with a selection of other standard methods of inferential statistics. RESULTS AND CONCLUSIONS Readers who are acquainted not just with descriptive methods, but also with Pearson's chi-square test, Fisher's exact test, and Student's t test will be able to interpret a large proportion of medical research articles. Criteria are presented for choosing the proper statistical test to be used out of the most frequently applied tests. An algorithm and a table are provided to facilitate the selection of the appropriate test.