Figure 3From: Towards the prevention of acute lung injury: a population based cohort study protocol Power for a matched case control study of 500 ALI patients matched to 500 controls where the risk factor occurs at 10%, 5%, or 1% prevalence in the controls and the false positive rate is 0.05. As depicted, if 5% of the controls experience delayed fluid resuscitation which increases the risk of ALI by 2 fold, then the study has about 82% power to reject the null hypothesis.Back to article page