From Test method, select the method for estimating the rates. When the samples are equal and large, the default method, Estimate the rates separately, is preferred. If the samples are equal but small, the default method is less accurate.
Select Use the pooled estimate of the rate only when the Hypothesized difference is equal to 0. When you select the pooled method, Minitab calculates the confidence interval based on the default method of estimating the rates separately, not on the pooled estimate of the rate.