Useful concepts for critical appraisal: 3. association, outcomes and errors

There is an increasing volume of research undertaken within orthodontics and with this comes a need to evaluate what is available. This short series aims to help the orthodontist revise basic concepts of critical appraisal and pertinent statistics. Clinical Relevance: Critical appraisal skills are valuable tools that can aid clinical decision-making. In this final article, we review ways in which associations and outcomes are commonly presented and discuss various types of error studies.