A one-sample Z-test is used to test if the mean of one population variable (m) is different from a reference value.

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.

·    sample size - the number of observations in the sample.

·    difference (effect) - the difference between m and the reference value.

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.

A dietician wants to determine if the mean percentage of saturated fat in cooking oil from a retail vendor is different from the advertised value of 15%. Previous tests indicate that the standard deviation is 2.6%. The dietician believes that a difference of 1.5% or larger is meaningful.