topic Re: proc shewhart - run tests on subset of input data in Statistical Procedures

proc shewhart - run tests on subset of input data

kdp — Mon, 01 Nov 2010 21:56:06 GMT

Hello,

I am using a data set in proc shewhart that has 180 observations for each by group combination. I would like to use the 180 observations to calculate all the statistics and display on the chart. However, I would only like to run the tests on the last 30 days. Basically, for the first 120 observations, it should not display if a test was violated or not - only for the last 30 observations.

Is this possible? I don't mind using multiple proc shewhart procedures to get around this issue.

Thanks,
kdp

Re: proc shewhart - run tests on subset of input data

Paige — Tue, 02 Nov 2010 12:07:48 GMT

I think you have figured out the basic procedure.

First, run PROC SHEWHART on all data, tell it to create no charts, and save the limits to a file.

Second, run PROC SHEWHART on just the data you want to chart, tell it to use the limits calculated above.

Re: proc shewhart - run tests on subset of input data

kdp — Tue, 02 Nov 2010 14:51:54 GMT

I actually want to chart all 180 observations. I just want it to show test violations in the last 30 observations. There might have been test violations in the first 120 days, but I don't want it to show on the chart.

I think that this might not be possible. 😞

Re: proc shewhart - run tests on subset of input data

Paige — Tue, 02 Nov 2010 15:20:11 GMT

I am not aware of a way to do this with PROC SHEWHART commands. It is probably possible using ANNOTATE graphics.