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anl
Turkey
8 Posts |
 Posted - 11 Dec 2015 : 08:37:20
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Hello there,
i want to develop a simple code which is mean-range-chart. And i get three datas one hour, and then five datas second hour and finally seven datas third hour.
But in the code, i cannot find the method that is dynamic changes. i just want to change sample size.
in my search on the docs(spc chart dotnet), i found mean-range-chart-vss but i dont understand.
if there is a basic code about the problem, please explain how to solve.
Thanks in your help.
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quinncurtis
1586 Posts |
Posted - 11 Dec 2015 : 09:01:53
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Standard Mean-Range (XBar-R) charts only support fixed sample size. There is no such thing as a Mean-Range chart with variable sample size, like you describe. We do not know where you are coming up with "mean-range-chart-vss". According to SPC Chart textbooks, the closest you can come is a Mean-Sigma chart with variable sample size (our MEAN_SIGMA_CHART_VSS) chart, which we do have. See the manual and the example program VariableSampleSizeControlCharts.BatchXBarSigma. This will produce varying control limits (dependent on sample size) for each sample interval. Though you certainly need more than three sample intervals in order to produce a usable graph. Also, your sample size per interval values (3, 5, and 7) are considered small for a Mean-Sigma chart.
Or, you can just use an Individual-Range chart, which uses just one sample per sample interval, and treat each measurement as an independent sample group. This will result in 15 (3 + 5 + 7) sample intervals for the chart, and produce fixed control limits. |
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sample size problem
