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Want to understand Poisson Capability Analysis?

QI Macros will calculate it for you!

Using u Chart data in columns B and C, the QI Macros Poisson Capability Template will create the charts and calculations for you!

NOTE: Make sure that not only is your data stable, but that it follows a Poisson Distribution, prior to inputting your data into this test. If your data is unstable and/or does not follow the Poisson Distribution, the calculated results may not be reliable.

Analysis (Based on Output Shown Above)

• The u chart is in control so capability analysis is possible. (Out of control data, as mentioned above, is not recommended)
• The Cumulative % Defective chart is also pretty stable.
• The Defective Rate chart shows points evenly distributed on either side of the average, so distribution is Poisson.
• If the Upper Confidence Interval (UCI) for DPU (cell AB5) is greater than the target DPU (cell AB11), you cannot be 95% confident that the process is capable.

This template can be opened by selecting the "Capability Templates" drop-down menu and choosing "Poisson Capability":

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