David is a statistician. He has a sample size of 40 (which he cannot change). What element of his hypothesis test can he adjust to minimize the probability that he incorrectly rejects the null hypothesis?

Incorrectly rejecting a true null hypothesis is a Type I error. Its probability is controlled by the significance level, α, so David can reduce that probability by choosing a smaller significance level. The sample size is fixed, and the population mean, sample mean, and population standard deviation are not the test setting that directly controls the Type I error rate.

AI-written and checked against the verified answer.