How sort data measurement to create control chart's?

Discussion in 'SPC - Statistical Process Control' started by heykylt67, Oct 13, 2017.

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1. heykylt67New Member

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Hello, at the beginning I would like to apologize for language errors because Eglishi is not my former language. I have a problem with creating an x-R control card.

I have a detail, I do a series of measurements of the hole diameter - 200 measurements = pieces. How to group data to create a control card. I mean test numbers x1, x2, x3, x4, x5 etc - these are the columns. How do I sort the data in rows? Is it just a series of consecutive measurements?

I will be happy to help. Regards

2. Bev DModeratorStaff Member

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Control charts display your measurements in the time order of production.

The data should never be sorted in any other way.

Are you measuring 200 sequential parts or is there some sample plan (example: 5 sequential parts, wait some time and take 5 more sequential parts)? This will determine how the data are grouped and what ‘average’ & standard deviation are calculated

3. tony sWell-Known Member

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If I collected data this way:

The columns will represent the time order of production (in this example daily). Here I have 20 subgroups (k) (i.e. columns). The subgroup size or sample size (n) is 5 (X1 to X5) (i.e. rows).

In collecting measurements for X1 to X5 you should consider the following:
X1 to X5 should represent only a single tool, die or cavity;
X1 to X5 should be collected at appropriate times that reflect the opportunities for change (e.g. hourly, per shift);
X1 to X5 can be collected in an unpredictable manner i.e. vary a bit from the specified collection time.​

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