Assuming you have a data table that has a column that indicates the week and a column that contains the measurement values, with the Spec Limits populated as Column Properties for the measurement Column.
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Go to
Analyze=>Quality and Process=>Process Capability
Fill in the Y, Process variable and place the column that has your week value into the "By" selection area
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In the output report window, hold down the CNTL key, and then click on the red triangle for the Process Capability, and select
Summary Reports=>Within Sigma Summary Report
Holding down the CNTL key will signal JMP to create the report for all of the Weeks.
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Right click on the summary report, and select
Create Combined Data Table
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This will create a new data table that has all of the Cp/Cpk information for each week, which you can then use as your report
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Jim