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A question for Reigle Stewart

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  • #35228

    Dr. Steve W.
    Participant

    Mr. Stewart,
    Since you know Dr. harry so well, you might know the answer to this question: how was the sample size formula (given delta, SD, alpha and power level) derived? It does not give the same answer Minitab gives (My understanding is that Minitab uses iterative algorithm to solve for sample size). I did some search but did not find anything that helps me understand the formula was derived. If you could shed some light, I would appreciate it greatly.

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    #98517

    Reigle Stewart
    Participant

    Dr Steve W: You may recall a book by Dr. William
    Diamond about DOE. He had a general equation for
    sample size (equal variances, group comparison). The
    equation is: N1 = N2 = 2(Z.a + Z.b)^2 * V / D^2. Once this
    equation is computed, the computed N is used to find the
    values of t.a and t.b (t distribution) during the second
    computation. So, we have a single iteration of the
    equation that is used to find the second solution. If this
    does not match the Minitab output, I don’t know what to
    say. Perhaps call Minitab or maybe Dr. Terry Zimmer
    knows (former Minitab statitician). Reigle Stewart

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    #98580

    Disappointed
    Participant

    Based on previous posts, Dr. Steve W should know the answer to this one.  What happened?  Has Stan’s insults hurt your self esteem?  And all Reigle did was to reiterate the formula rather than provide any new insight.  Bring back the Shroeder thread, at least we were learning something.

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