point suppression

[Former Member]

Hi

I have an ispc chart based on some inspection characteristics in ECC.

It works fine except for point suppression. Points are suppressed properly, but if the subgroup size is greater than 1, then the chart will not display the suppressed point, and therefor the point cannot be unsuppressed. This is the case regardless of the setting "Show Suppressed Points" in the template, and regardless of choosing "Show Suppressed Points" under "Query Properties" on the chart context menu.

This behaviour is the same for any type of chart, e.g. XBAR, XBAR-RANGE etc.

When I right-click on the chart and choose "SPC Results" the data for the suppressed point is not shown in "Upper Chart Data Points", but is shown in "Chart Data Values".

I am using 12.0.11 build(14)

Can anyone help?

Thanks

Nick

[jcgood25 · Accepted solution]

So you are looking to suppress a subgroup point containing multiple points displayed in one data marker?

Since the subgrouping is not based upon shared point characteristics like a batch number (buckets based upon ), the ID tied to the marker in the chart is not 'real'.

If you supress each of the 'bad' points using subgroup = 1, then toggle the subgroup size to something greater than 1 do you get to the desired solution?

[Former Member · Accepted solution]

Jeremy

I think I am missing a trick here.

Is there a way to group data together other than setting subgroup size?

But to answer your question, If I force the subgroup size to 1 then all of the sub-points appear on my chart as suppressed, I then force it back to 5 and the point disappears again.

It does however solve a problem I was having that the Control limits were not being calculated, they now are on the XBAR graph. However thay are still not being caculated on the XBAR-RANGE. Any ideas?

Edited by: Nick Stannage on Sep 15, 2010 3:43 PM

Edited by: Nick Stannage on Sep 15, 2010 4:12 PM

[Former Member · Accepted solution]

Actually, when suppressing the point with subgroupsize set > 1, the Control Limits are NOT calculated, and NOT shown on the chart. Therefor alarms are not shown either.

[jcgood25 · Accepted solution]

There is nothing special about grouping - subgroup size of 2 just averages every 2 datapoints from your query and gives you 1/2 the original values, etc. Aside from doing something with a GROUP BY in your query or massaging the dataset before sending it to the iSPCChart, subgrouping in very utilitarian.

One cool thing that would work would be to use the attribute highlighting feature. This would give the visual appearance of grouped points, sharing the same attribute. There is a setting to do this in the template, the right click menu, or with a simple passthrough in javascript.

I'm not sure about suppressed points even being relevant when subgroup > 1, since you're attempting to exclude a point that is really an aggregate average point, and the associated attributes that make it unique are really not distinctive to the outlier you would be excluding by suppressing it.

[Former Member · Accepted solution]

Actually I just realised what I am doing wrong, my data points were not unique.

When I added in another field to the ID it all started working fine.

Thanks for your help

Nick

Edited by: Nick Stannage on Sep 17, 2010 8:43 AM

[Former Member]

Hello again.

I thought I had this fixed, but it is still not acting the way I would expect, and hopefully someone can explain to me what I am doing wrong.

Here is a simple set of data

Unit Test Value 1    a    3 1    b    4 1    c    3 2    d    3 2    e    7 2    f    6 3    g    3 3    h    3.2 3    i    3

When I load this into a SPC XBAR-Range chart with ID column set to Unit, and Subgroup size set to 3 I see what I would expect

XBAR : 3.33, 5.33 and 3.07

Mean : 3.91

RANGE: 1, 4 and 0.2

If I try to suppress the middle unit, the datapoint disappears completely from the graph, and the UCL and LCL calculations are no longer made.

With ID column set to Unit AND Test, I see the same basic chart. This time when I try to suppress the middle point I get the following results

XBAR : 3.33, 5 (marked as suppresseed) and 3.07

Mean : 3.65

Range: 1, 4 (marked as suppressed) and 0.2

LCL and UCL are calculated, but as with the mean, seem to be calculated on 8 points, rather than the 6 I would have expected.

If I suppress each point of Unit 2 individually, this behaves the same way as the earlier test, with the middle unit disappearing entirely, and Control limit calculations not being done.

Hopefully all this makes sense, and someone will be able to tell me how to fix my data, or confirm that there is something wrong with iSPC that I can take back to SAP.

Thanks

Nick