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When will Box-Cox Transformation be available

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  • #37402

    ROSS
    Member

    Hi:
        We can use Box-Cox Transformation in Minitab to transfer some nonnormal distribution date to normal distribution,  but it is not available in any case, can somebody tell me in what case it will avaliable and in what case it will unavailable?
       Tks! 

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    #110107

    ROSS
    Member

    Hi:
       Pls somebody who has experiments on it help me.
     Tks!

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    #110112

    John Noguera
    Participant

    Tony,
    Your question is a bit unclear. If you are asking about the availability of columns for Box-Cox Transformation, Minitab hides any columns that have text, or cells with  negative or zero values.

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    #110131

    Ray M.
    Participant

    Your data has to be positive to use Box-Cox, if that’s what you are asking.

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    #110162

    ROSS
    Member

    John , Ray:
         Thanks for your feedback!
        Yes, column with text or cells with  negative or zero values will be hided and can not do box-cox transformation. But also we may not successs even we meet the erquirements of Mnitab, do you know what kind of data(meet Minitab box-cox requierment) we can success?
       Tks!
       

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    #110232

    ROSS
    Member

    Ray:
       Thanks for your feedback!
       Yes! The data should be positive, but even the positive data, we will fail at box-cox transformation, my question is waht kind of positive data can be available at box-cox, and what kind of can not?
      Tks!

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    #110233

    Nanni
    Participant

    Could you be more specific, please.
     
    The box cox transformation need  “non-negative” data. If you have negative data or with zero’s, you have to add a unit until you have all the data non-negative.
     
    And, Why the B-C transformation cannot use non-negative data? Because one of the transforamation uses the function “logarithm”, and you can easy proof in excel that —>
                ln(0) or ln(any negative number) = #NUM!
    It means that don’t exist.
     

    You could find more information in Montgomery’s Book (Design of Experiments)
    If you don’t have it, you could find some information at internet. Anyway, if I could help u in anything else, don’t hesitates.
     
    Hi from Mexico !
    good luck!

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