21. Tsang and colleagues (2009) conducted a review to examine the statistical power of studies that had compared patients’ experiences of serious adverse events (such as a life-threatening medical event) during randomized controlled trials of medical treatments. They identified six studies that reported the results of statistical analyses to test whether the number of adverse effects experienced by patients receiving one medical treatment differed from the number experienced by those receiving a different treatment. Tsang et al. summarized their results as follows: “Three of the six studies included in this analysis reported non-statistically significant differences in serious adverse event rates, and concluded that there was no difference in risk despite [having power] of less than 0.37 to detect the reported differences” (p. 610). They also noted that: “A high probability of type II error may lead to erroneous clinical inference resulting in harm. The statistical power for nonsignificant tests should be considered in the interpretation of results” (p. 609). Explain the results of this review to a person who understands hypothesis testing and decision errors but has never learned about effect size or power.