Are Difference-bar & R appropriate for drift check for working standards? What are the formulas for these charts? What other method of charting out there for checking long-term and short-term gage stability?

Hi
What exactly is a Difference-bar?
What do you want to do? Do you have a gauge that you would like to test in time?

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It is a pair of short run SPC charts available in WinSPC. I'm not quite sure what formulas they used for difference-bar & R. I was thinking of monitoring the gage stability with it. The gage is a wire pull tester.

R-bar sounds like another name for CUSUM or functions similarly. R-bar plots the difference between sample value and a target value I'm guessing? I worked in a high carbon wire mill for 10+years in process control and product test. We used CUSUM a lot and I found it to be a very useful chart to monitor process drift.