iSixSigma

Bill McNeese

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  • #195612

    Bill McNeese
    Member

    MBBinWI is correct. You need to look at your measurement system. If you use your data to create an individuals control chart, you will see that the moving range chart only has 3 possible values. This is what Dr. Wheeler calls “chunky data” – it is excessive round off error in the measurement. This leads to out of control points on the X chart, which may not be valid. I have attached a workbook with the control chart in it.

    You can still calculate the capability using the standard formulas – it just doesn’t mean much because of the measurement system. Always look at the control chart before doing a process capability analysis. The control chart will tell you what is happening in the process.

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    #195610

    Bill McNeese
    Member

    It seems to me that this got complicated very fast. You have several customers with different delivery requirements. Let’s assume you are just looking at whether the shipment was on-time for a customer. I would start by making sure that you have a good operational definition of that requirement. Say customer A wants the product this Friday. You won’t get it done until Monday. So, you call the customer and ask if Monday is OK. He says yes. Did you still meet the delivery requirement? Many companies would say yes – after all, it makes there on-time delivery look better. Make sure you have good operational definitions in place for your delivery requirements or your analysis will not be valid.

    From there I would keep it simple. If you are looking at on-time delivery, I would simply plot the % of on-time deliveries (per day, per week or month depending on the number of shipments)using an individuals control chart. Your capability is whatever your average % on-time is once you have enough data (only need 4 to 5 points to start the chart; use historical data if operational definitions were OK) and is stable. Then use Pareto diagrams to look at reasons for late deliveries, by customer etc. That should help guide your problem solving efforts.

    The different delivery requirements will most likely have different means/medians. I would not worry about normality. You may well not have enough points with each different requirement to test that and the objective is to improve performance versus the delivery requirements.

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    #193999

    Bill McNeese
    Member

    The best approach is to put together a team of the pickers to work on improving the picking – involve them finding the reasons for the error and improving the process. Follow a problem-solving methodology.

    It has to be no blame approach – as stated above, most of the issues come the system – the way the process was put together and the way that it is managed on a day-to-day basis. Use control charts with Pareto diagrams.

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    #189879

    Bill McNeese
    Member

    Perhaps I don’t understand. You could see the segmented discussion if you wanted by selecting the by thread option in the old forum. I really liked the ability to see individual posts if I wanted or by thread. I can’t see individual posts here. Registration is fine. Didn’t you use to have the ability to download files? Maybe you did talk to the customer to see what they wanted and I am in the minority. This is still a good web with lots of useful information.

    Bill

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    #189870

    Bill McNeese
    Member

    It has been awhile since I was here. New format. Always looked for your name and Stan – and a few others. This is not good. There used to be many posts on a day. What happened?

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Viewing 5 posts - 1 through 5 (of 5 total)