SPC calculated control limits

[Former Member]

SPC Charts

I can have three SPC Charts that have the same query and display, but different values and control limits could be missing from one or all charts. How are the control limits calculated and why is it when I take the same data and put it in another SPC program I get the control limits where they are supposed to be and xMII does not display them?

[jcgood25 · Accepted solution]

I looked at the files you sent and the problem appears to be that you have invalid values in your dataset. By doing a right-click on the chart and looking at the summary stats I could see a square character (sort of like a NaN concept) and when looking at the data there were a handful of <Avg30>NA</Avg30> values in the xml dataset you sent me. So when the auto calc for control limits was done on this as the ValueColumn they showed up at 0 on the chart because there was nowhere else to go. By making these <Avg30/> in the xml I was able to refresh the chart and see the control limits at LCL:37.12, CL:48.01, and UCL:58.90

What is the source of the data for Server="NWA_Euclid"?

Regards,

Jeremy Good

[Former Member · Accepted solution]

So if I eliminate all data in my value column that is not a numeric value, I should get better looking charts?

NWA_Euclid is an Database on our SQL Server

[jcgood25]

Can you email me or post the xml spc detail results for one of your charts that is not determining the control limits the way you want?

To get xml results just hold down the Ctrl key while doing a right-click spc results detail.

The actual display template would be helpful too - to see your settings for control limits since there are several ways to do this and have differing prioritization when multiple ways are setup like auto-calc and ext. data mapping, etc.

Regards,

Jeremy

[jcgood25]

Are you changing these parameters with JavaScript or through html <PARAM/> entries in the web page to differentiate your 3 views? If you are doing this with JavaScript make sure you do a document.APPLETNAME.updateChart(true); after setting your query object params.

The auto calculation effort is done based upon the query dataset on the server side and then shown by the chart.

Is your ValueColumn always a numeric column of data?

Best Regards,

Jeremy Good

[Former Member]

function doSel(obj)

{

var df = document.frmMain;

for (i = 1; i < obj.length; i++)

{

if (obj<i>.selected == true)

{

document.ind_SK_Centers_Weld.getQueryObject().setParam(4,df.RecordCount.value);

document.ind_SK_Centers_Center.getQueryObject().setParam(4,df.RecordCount.value);

document.ind_SK_Centers_Hold.getQueryObject().setParam(4,df.RecordCount.value);

document.ind_SK_Centers_Weld.updateChart(true);

document.ind_SK_Centers_Center.updateChart(true); document.ind_SK_Centers_Hold.updateChart(true);

}

}

}

This is the function that occurs when I select a record to modify the existing SPC charts. I already include the applet names in the update chart.

[Former Member]

Any help here?

[jcgood25]

Your question is a little vague, can you clarify? Are you auto calculating control limits or passing them into the chart template on the Ext. Mapping tab?

Best Regards,

Jeremy

[Former Member]

I am auto calculating the SPC control limits.

I just don't understand why my charts do not show the control limits when I use the same dataset, but change the Param for product or something. Why do control limits disappear from the chart when I need them on the chart 100% of the time. I make no modifications to the display settings of the chart. I only pass a Param. This param is in the product field.