Simple Statistical Tests and P Values

Reporting of studies in the surgical literature usually contains the use of statistical principles such as estimation and hypothesis testing. The goal of this chapter is to introduce and describe the statistical principles for applied use by surgeons. We include a clinical scenario and have identified a previously published randomized controlled trial to appraise. The discussion focuses on the statistical analysis of this trial including descriptive statistics, test statistics, and how they can be computed with reliable statistical software. We then reproduce these statistical test results and compare our results with those reported. Along the way, we comment on the assumptions that go with these tests. We include a discussion on confidence intervals (CIs) and P values to help interpret the findings in the appraised paper.