Statistical tests in orthopaedic research

An understanding of the basic principles of statistical analysis is vital before commencing research. This article aims to provide a concise overview of this extensive subject, highlighting the important concepts. Statistical analysis should be considered at the planning stage of any study so as to establish hypotheses, specify the primary outcome of interest and undertake a sample power calculation. The research question, scale of measurement and distribution of the outcome variable all have a bearing on the appropriate choice of statistical test. A statistical test can only be employed if the distribution assumptions of the test have been met. The interpretation of significance must be tempered by limitations of the method of analysis, as well as recognizing the variability of the effect of interest using an interval estimate. The various descriptive statistics in diagnostic studies are also explored.