Tolerance Interval

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Use to produce an interval estimated to contain a specified proportion of a population.

Tolerance Interval for Proportion (Normal Distribution)

1. From an open JMP data table, select Analyze > Distribution.
2. Select one or more continuous variables from Select Columns, click Y, Columns (continuous variables have blue triangles), and click OK.
3. From the Distributions report window, select Tolerance Interval under the red triangle next to the variable name.
4. Select the confidence level and specify proportion of the population you desire the interval to cover. Choose Two-sided or one-sided interval. Here we chose 95% confidence, 90% proportion to cover, and two sided.
5. Choose to Assume Normal Distribution if you believe that is an appropriate model to use to describe the distribution of the variable for the population. Click OK.
   Note: A goodness-of-fit test (not shown) indicates that a normal distribution is appropriate.
   
   JMP will add a table displaying the lower and upper bound of the Tolerance Interval based upon assumption of a normal distribution.

Interpretation:
It is estimated, with 95% confidence, that 90% of pins produced by this process that these data can be considered a sample from will have a Weight between 17.3 and 23.5.

Tolerance Interval for Proportion (Non-Normal Distribution)

1. Follow steps 1-3 above.
2. In the Tolerance Interval Dialog box, choose Nonparametric method. Click OK.
   Note: A goodness-of-fit test (not shown) indicates that a normal distribution is not an appropriate model to use.

JMP will add a table displaying the lower and upper bound of the Tolerance Interval for any continuous distribution.
Note: The actual confidence level achieved may be larger than the value specified. Here it’s 97.6% confidence.

Interpretation:

It is estimated, with 97.6% confidence, that 90% of this process that these data can be considered a sample from have values between 5.23 and 17.2.

Coating.jmp (Help > Sample Data Folder > Quality Control)

Process Measurements.jmp (Help > Sample Data Folder)

Visit Basic Analysis > Distributions > Options for Continuous Variables > Tolerance Intervals in JMP Help to learn more.