Evidence-based practice in nephrology: critical appraisal of nephrology clinical research: were the correct statistical tests used?

Abstract

Nephrologists rely on valid clinical studies to inform their health care decisions. Knowledge of simple statistical principles equips the prudent nephrologist with the skills that allow him or her to critically evaluate clinical studies and to determine the validity of the results. Important in this process is knowing when certain statistical tests are used appropriately and if their application in interpreting research data will most likely lead to the most robust or valid conclusions. The research team bears the responsibility for determining the statistical analysis during the design phase of the study and subsequently for carrying out the appropriate analysis. This will ensure that bias is minimized and "valid" results are reported. We have summarized the important caveats and components in correctly choosing a statistical test with a series of tables. With this format, we wish to provide a tool for the nephrologist/researcher that he or she can use when required to decide if an appropriate statistical analysis plan was implemented for any particular study. We have included in these tables the types of statistical tests that might be used best for analysis of different types of comparisons on small and on larger patient samples.