Posts: 4119
From:West Chester, OH, USA
Registered:

posted 11 July 2000 07:12 AM               

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I admit ignorance in matters of Run Charts.

1. Does one compute control limits for run charts? If so, what is the basic methodology?

2. What is the intent (Value? Role?) of a run chart?

[This message has been edited by Marc Smith (edited 11 July 2000).]

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Posts: 275
From:ILLINOIS
Registered: Mar 2000

posted 11 July 2000 08:01 AM               

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Run charts are simply plots of process characteristics against time or in chronological sequence. They do not have statistical basis, but are useful in revealing
trends
relationships between variables

Check out this site for Run chart details -
http://lorien.ncl.ac.uk/ming/spc/spc0.htm

Regards
Jim

[This message has been edited by Jim Biz (edited 11 July 2000).]

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Posts: 4119
From:West Chester, OH, USA
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posted 11 July 2000 08:10 AM               

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Thanks. That's pretty much as I understood them - just a 'view' of a process trend. But - I still don't understand how control limits would be computed.

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Posts: 275
From:ILLINOIS
Registered: Mar 2000

posted 11 July 2000 10:59 AM               

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IMHO "computed limits" should in most cases not be part how they are used. Although a reasonable upper or lower "Goal" could be "chosen" depending on the variables interaction within a given timeframe. They can however be used to pass information along to the interested party.... Example If I change "A" what happens to "B" and how long does any change take to show an effect.

Regards
Jim

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