The 2-sample Poisson rate procedure conducts a hypothesis test for the difference between the occurrence rates of two Poisson distributions.

Minitab's power and sample size capabilities allow you to examine how the following test properties affect each other:

·    power - the probability of being able to detect an effect of a given size. (The effect is the difference between population rate 1 and population rate 2.)

·    sample size - the number of observations for each sample.

·    comparison rate - the rate you want to compare to the baseline rate.

If you provide values (or sets of values) for any two of these properties, Minitab will calculate the associated values for the remaining property.

By default, all calculations are based on an a-level of 0.05. However, you can select any value between 0 and 1.

You are an analyst for the postal service, and you want to compare two post office branches to determine which has the greater daily rate of customer visits. The historical rate is 250 customers per day, and a difference of 10 customers per day is meaningful.