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Hypothesis test for the difference of the difference of means?

  1. Sep 16, 2014 #1
    Hello all,

    Consider 3 different samples. Each sample is independent.

    1: 23, 25, 21, 22, 21, 22, 20, 23, 19, 22, 19, 21
    2: 28, 27, 27, 29, 26, 29, 27, 30, 28, 27, 26, 29
    3: 23, 20, 25, 21, 22, 23, 21, 20, 19, 20, 22, 21

    I am being asked to test whether μ2 - μ1 = μ3 - μ2 with 99% confidence. How am I meant to perform this test? I know how to test for the difference of means, that's quite simple, but how does one test for the difference of differences?
     
  2. jcsd
  3. Sep 17, 2014 #2

    WWGD

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  4. Sep 17, 2014 #3
    ANOVA tests whether the means of all samples are the same, so in this case an ANOVA test would test whether μ1 = μ2 = μ3. I need something rather different, testing whether the differences between specific pairs are equal.
     
  5. Sep 17, 2014 #4

    WWGD

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    Sorry I misread the post.
     
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