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Thread: Factorial experiment in CRD with unequal replications

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    Factorial experiment in CRD with unequal replications




    Hi guys, i am a graduate student in statistics.

    i want to test for the main and interaction effect of 3 treatments on a group of patients. let say i have treatments A, B and C. each with 2 levels, presence and absence. So i decided to perform a 2^3 factorial Experiment in a Completely Randomized Design(CRD).
    Now as the data arises from medical fields and test is not performed by me, i don't have equal no. of replications for all the 8 treatment combinations. And I cant find anywhere in my textbooks on how to deal with a Factorial analysis in CRD with unequal replications, and thus i can't find the sum of squares due to the treatment combinations and perform the tests. And also i want to know if i can apply standard Yates' algorithm for 2^3 factorial analysis.
    Can you guys help me please? any help will be appreciated. Also if you can provide answers using R or MINITAB that is okay for me. But other softwares like SAS, i haven't used them yet.
    Last edited by skyakash; 03-17-2016 at 12:47 PM.

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    Re: Factorial experiment in CRD with unequal replications

    This is an unbalanced design. In Minitab, use GLM (General Linear Model).

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    Re: Factorial experiment in CRD with unequal replications

    can you please elaborate the ANOVA table? i mean i can't understand how in Minitab they are obtaining the sum of squares due to the factorial effects. And so if you can explain them theoretically that will be great.
    Last edited by skyakash; 03-17-2016 at 09:40 PM.

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    Re: Factorial experiment in CRD with unequal replications


    In Minitab: Stat > ANOVA > General Linear Model > Fit General Linear Model > Help > See Also > Methods and Formulas > Adjusted Sum of Squares

    See also https://www.ma.utexas.edu/users/mks/...unbalanced.pdf and http://jonathantemplin.com/files/ano..._lecture11.pdf

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