Control chart for groups of data
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Ron.
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June 19, 2008 at 9:59 am #50332
I have 6 lots of data from a process and would like to plot using IM-R chart or similar. I was wondering is it possible to put all the data onto the same chart and have limiits calculated for each section (x6)? So I can show before improvement, during and after all on the same chart? Do I just need to use subscipts for each group and if so how do I then chart on 1 sheet?
Thanks0June 19, 2008 at 10:26 am #172975Whats the harm in using different charts. It would look neat as well
0June 19, 2008 at 11:57 am #172979
Bower ChielParticipant@Bower-ChielInclude @Bower-Chiel in your post and this person will
be notified via email.Hi Richard
What software are you using?
Bower Chiel
0June 19, 2008 at 12:08 pm #172980Hi Bower,
Minitab, Yes sorry that was an after thought.
Richard0June 19, 2008 at 12:28 pm #172983
Bower ChielParticipant@Bower-ChielInclude @Bower-Chiel in your post and this person will
be notified via email.Hi Richard
You can achieve what I think you require by having one column for your individual data values and another for the lot number: – 1, 2, 3, …. . Under I Chart Options the Stages tab enables you to define stages using the lot number column.
Good Luck!
Bower0June 19, 2008 at 12:46 pm #172984Good one Bower
0June 19, 2008 at 3:05 pm #172997Hi Bower,
Thanks for that. I had tried that and didn’t give em exactly what I was after? Its along the right line but I would like to disply it on a continuous single chart with limits recalculated for each section in sequence? Perhaps you cannot do it but I’m sure I’ve seen it done somewhere. I’ll keep trying, any other ideas?
Richard0June 19, 2008 at 3:21 pm #172999
Bower ChielParticipant@Bower-ChielInclude @Bower-Chiel in your post and this person will
be notified via email.Hi RichardIf you post an e-mail address I’ll send you some more details.Bower Chiel
0June 21, 2008 at 5:05 am #173069can u send me the details
my id is [email protected]0June 21, 2008 at 5:26 am #173070
Venugopal GMember@Venugopal-GInclude @Venugopal-G in your post and this person will
be notified via email.Hi Richard,
Can U send me the e-mail ID so that I can post an example. If I understood correctly, U are looking for a single chart with both before and after situations and also the control limits have changed indicating the improvement and there is a shift in the mean.
Regards,
G. Venugopal
0June 21, 2008 at 5:33 am #173071Hi Richard!
You will have one more Tab in the I-MR option called “Display”. Under it just tick the “display control limit/center line labels for all stages”. Click OK. u can see the means and comtrol limits at all stages.
Regards
Viswa0June 24, 2008 at 9:02 pm #173172I prefer using one chart showing the before and after with the computed ucl and lcl based on pre change.
0June 25, 2008 at 7:29 am #173180Hi Venugopal / Bower
My email address: [email protected]
Thanks for your help
Richard0June 25, 2008 at 11:02 am #173182You have described the requirement for the most powerful shewhart chart..the Xbar & R chart. It displays within and between process variaiton.
0June 25, 2008 at 11:09 am #173184Hi Thanks everyone I’ve cracked it! it was as suggested by Bower the Stges under IMR Option tab. I must of had other items selected whilst rying to find the right solution that was confusing issues.
Cheers0June 25, 2008 at 4:35 pm #173198ricjard,
6 groups of data is not sufficient to calculate fixed control limits. Typically a minimum of 25 to 30 sample lots of data is required statistically.0 -
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