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From: | Alan Mead |
Subject: | Re: bonferroni correction to a mann whitney u test? |
Date: | Fri, 28 Oct 2016 08:11:47 -0500 |
User-agent: | Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 |
PSPP implements a subset of SPSS syntax and it sounds like PSPP does
not accept that syntax. I don't see this option in the manual:
https://www.gnu.org/software/pspp/manual/pspp.pdf As a work-around, you could run the M-W test multiple times and apply a Bonferroni-corrected alpha, right? If you have 24 groups to compare, don't you have 24*23/2 = 276 paired comparisons to make? If controlling the Type I error at the expense of enormously magnifying the Type II error is your goal, Bonferroni is a good way to go. OTOH, if you care about the Type II error rate, I'd recommend that you do the comparisons without any correction and then calculate how many are significant to the number expected by chance. You said that "all" of the comparisons are significant; if that's literally true, then comparing the 5% expected by chance to 100% observed outcomes, I'd conclude that virtually all of your groups are statistically significantly different. This doesn't sound like a situation which requires complex statistical decision-making. -Alan On 10/28/2016 1:03 AM, Jennifer L A
Shaw wrote:
-- Alan D. Mead, Ph.D. President, Talent Algorithms Inc. science + technology = better workers +815.588.3846 (Office) +267.334.4143 (Mobile) http://www.alanmead.org I've... seen things you people wouldn't believe... functions on fire in a copy of Orion. I watched C-Sharp glitter in the dark near a programmable gate. All those moments will be lost in time, like Ruby... on... Rails... Time for Pi. --"The Register" user Alister, applying the famous "Blade Runner" speech to software development |
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