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Ignore Outlier in Minitab 16.2.3

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This topic contains 9 replies, has 3 voices, and was last updated by  Thomas Subia 1 year, 1 month ago.

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  • #54385

    Adam Nowakowski
    Participant

    Hello all,

    I’m trying to figure out how to ignore a data point in minitab 16. The point is an outlier with assignable cause. I’d like to keep it on the control chart, but remove it from the calculation.

    Thanks,

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    #195150

    Joel Smith
    Participant

    @adamnowakowski – In the dialog for the control chart, there will be an Options button – for example “I-MR Options” or “Xbar-S Options”. Click on that and go to the “Estimate” tab, where you can specify which point or subgroup(s) you want to omit from calculations.

    Good luck!

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    #195152

    Adam Nowakowski
    Participant

    Hi Joel,

    Thanks for the response. I think it has gotten me closer to the answer, but I can’t seem to find exactly what your talking about. I have a I-MR Control chart with a clear outlier that I’d like to show but remove from the actual calculations. I am very new to Mini-tab so I’m not even sure what you mean by “dialog for the control chart”. Is this the actual chart, or the excel like data under it? I feel like I should be able to click on the outlier point and exclude it but nothing seems to be that option. I did find a graph options area on the graph, but it is grey’d out and I can’t select it.

    Again thanks for the help, it is much appreciated.

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    #195155

    Joel Smith
    Participant

    @adamnowakowski Sorry…to clarify I meant go back into Stat > Control Charts > Variables Charts for Individuals > I-MR and you’ll click on the “I-MR Options” button in there. You’ll need to know the row number of the point(s) to omit, and the easiest way to get that is just hover over the point on the chart.

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    #195156

    Adam Nowakowski
    Participant

    Joel,

    Thank you so much! I have been searching Google and been banging my head on this all day. You rock!

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    #195157

    Joel Smith
    Participant

    @adamnowakowski No problem! You can always get free tech support at 814-231-2682.

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    #199591

    Ramnag

    Hello Joel sir, how to ignore the outlier from the Xbar and R control chart, i tried what you told in previous msg, but it dosent work for me. how to specify tat row number in xbar and R chart options.
    pls help me i am doing my project work so
    Thanks

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    #199601

    Joel Smith
    Participant

    @Ramnag For a subgrouped control chart you enter the subgroup number. For example, if subgroup 12 has assignable cause you would enter “12” in that dialog. The subgroup number is labelled on the X-axis of the chart.

    Good luck!

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    #202483

    john christmas

    According me i just want to know how to run grubbs and dixon tests in minitab 16

    Bests regards

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    #202492

    Thomas Subia
    Participant

    John,
    Here’s how you run Grubbs or Dixon’s outlier test in Minitab.

    Go to Stat, Outlier test,
    Under options choose the test you wish to do.
    Be careful when you choose a outlier test method.

    Minitab suggests that if you don’t know whether your data include outliers, use the Grubbs’ test.

    There are options for Dixon’s test or Grubb’s test. For more information on those tests go to:

    As always look at your data with a Box Plot or a Q-Q plot just to see what your distribution looks like.

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