Overview for Sample Size for Tolerance Intervals

Use Sample Size for Tolerance Intervals to examine the relationship between sample size and the maximum acceptable percentages of population in the interval for tolerance intervals. Minitab displays intervals for two methods. The normal method is applicable only when the data follow a normal distribution. The nonparametric method is applicable for any continuous distribution, but is more conservative than the normal method.

For example, an engineer wants to calculate a tolerance interval for weld lengths that covers 96% of the population. The engineer calculates the sample size that is necessary to achieve a maximum acceptable percentage of 98%.

After you perform the sample size analysis, you can calculate the tolerance intervals. For more information, go to Tolerance Intervals (Normal Distribution).

Where to find this analysis

To perform a sample size for tolerance intervals analysis, choose Stat > Power and Sample Size > Sample Size for Tolerance Intervals.