| T O P I C R E V I E W |
| Bill Rokos |
Posted - 20 Mar 2014 : 21:28:01
Hello,
I am currently using the SPC Control Chart set to PERCENT_DEFECTIVE_PARTS_CHART_VSS. When my chart is complete it seems to be taking the first Sample Sub Group Size and using it to determine Defective %.
1. I load the chart type by calling: Chart.SPCChartType = SPCControlChartData.PERCENT_DEFECTIVE_PARTS_CHART_VSS;
2. I then go through my categories and build an array of defective count for each category. At the last element I add my total defective count.
3. After setting Table header info and control limits.
4. I call Chart.ChartData.SampleSubgroupSize_VSS = sampleSubGroup.TotalSampleCount; to set the number of samples per sample sub group.
5. I call chart.ChartData.AddNewSampleRecord(index, samplesArrayFromAbove, UniqueStringOfSampleSubGroupAsNote);
6. to set the scale I call chart.AutoScalePrimaryChartYRange();
7. Then to use current data I call chart.RebuildChartUsingCurrentData();
I am not sure what I am doing wrong. If you have any advice please let me know. Also if you need additional information please let me know.
Defects 14 17 5 11 10 7 5 21 13 19
Sample Count 74 60 62 54 67 70 51 71 62 69
Expected Def% 0.189189189 0.283333333 0.080645161 0.203703704 0.149253731 0.1 0.098039216 0.295774648 0.209677419 0.275362319
Actual Def% 0.189189189 0.22972973 0.067567568 0.148648649 0.135135135 0.094594595 0.067567568 0.283783784 0.175675676 0.256756757
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| 3 L A T E S T R E P L I E S (Newest First) |
| quinncurtis |
Posted - 24 Mar 2014 : 20:05:43
There does seem to be something wrong with that version of AddNewSampleRecord. We will have to investigate further and find what the problem is. |
| Bill Rokos |
Posted - 24 Mar 2014 : 17:49:07
Hello,
So I did a lot of testing on this. I think I figured out what is causing my problem. So to test I used your C# sample called VariableSampleSizeControlCharts. In the SimulateData() function of the PercentDefectivePartsControlChart.cs I was able to change the call slightly and reproduce the error.
In the sample code the VSS value works fine:
this.ChartData.AddNewSampleRecord( timestamp, samples);
If I change the call to:
this.ChartData.AddNewSampleRecord(i, timestamp, samples, "Note");
The value in this.ChartData.SampleSubgroupSize_VSS = numsamplespersubgroup - (int)(25 * ChartSupport.GetRandomDouble()); seems to be ignored. Can you help me determine if this is as designed?
Best Regards
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| quinncurtis |
Posted - 20 Mar 2014 : 23:57:13
Using your data, we reproduced the results you say are correct. Can you send us a zip file of a complete program which reproduces the results you say you are getting.
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