Confidence intervalsConfidence intervals provide information on how certain we are of the results of a study and help clinicians to decide whether the results are applicable to their patients. They permit us to draw inferences about a large population from a smaller sample of researchResearch participants. They tell us how confident we can be that the true population value lies within a range of estimates. Confidence intervals are calculated in various ways depending on the type of estimate and are impacted by the sample sizeSample size, number of events, the type of analysis and the degree of confidenceDegree of confidence that has been selected (i.e. 95 vs. 99%). We can use the confidence interval for hypothesis testingHypothesis testing by determining if our null hypothesis value (usually zero or one) is included within our confidence interval or not. Confidence intervals should be used alongside the minimal clinically important differenceMinimal clinically important difference to guideGuide clinical decisions, so that decisions are made on clinical and statistical grounds.