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Why am I getting different values of degrees of freedom for the s.

  1. #1
    jeng
    Guest

    Why am I getting different values of degrees of freedom for the s.

    I am trying to use excel to do some simple data analysis (t test). I am
    analyzing a few different sets of data with the same number of samples each.
    3 in a control group and 3 in a treatment group. By my understanding of
    degrees of freedom...there are 4 degrees of freedom (3+3)-2. For some reason
    though, for the different data (with 3 samples in each group) I am getting a
    different number of degrees of freedom (ie. 2 instead of 4). If I have the
    same number of samples in each analysis condition, shouldn't my degrees of
    freedom be the same??

  2. #2
    Mike Middleton
    Guest

    Re: Why am I getting different values of degrees of freedom for the s.

    jeng -

    Excel's Analysis ToolPak (Tools | Data Analysis) has three separate t-tests.
    You did not specify which one you are using.

    With 3 observations in each of the two samples, there will be df = 2 for the
    paired-sample test, df = 3 for the unequal-variance test, and df = 4 for the
    equal-variance test.

    - Mike
    http://www.mikemiddleton.com

    "jeng" <jeng@discussions.microsoft.com> wrote in message
    news:A3C97D43-A48C-4D9F-B1BA-9AECF14F4B73@microsoft.com...
    >I am trying to use excel to do some simple data analysis (t test). I am
    > analyzing a few different sets of data with the same number of samples
    > each.
    > 3 in a control group and 3 in a treatment group. By my understanding of
    > degrees of freedom...there are 4 degrees of freedom (3+3)-2. For some
    > reason
    > though, for the different data (with 3 samples in each group) I am getting
    > a
    > different number of degrees of freedom (ie. 2 instead of 4). If I have
    > the
    > same number of samples in each analysis condition, shouldn't my degrees of
    > freedom be the same??




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