Specify the risk level (denoted as α or alpha) for the test. Usually, an α of 0.05 works well. An α of 0.05 indicates a 5% risk of rejecting the null hypothesis when it is actually true (type I error).
The value of α is often set by industry guidelines. If you use a smaller value for α, such as 0.01, you can reduce the risk of a type I error. For example, if you perform an equivalence test using the default hypotheses, using a smaller alpha reduces the risk of claiming equivalence when it is not actually true. However, a smaller α also increases the risk that the test is overly conservative and does not allow you to claim equivalence when it is actually true.
The α value also sets the confidence level for the confidence interval. By default, the confidence level is (1 – α) × 100%. For example, if α is 0.05, Minitab calculates a 95% confidence interval.