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November 24th, 2017, 08:05 AM   #1
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Tukey test

I read the definition in Wikipedia and I don't understand a thing.
What is the Tukey test in a few words in Simple English!!!
Thank for answering or considering my post.
shaharhada is offline  
 
November 29th, 2017, 11:41 AM   #2
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When you compare multiple groups (such as group 1, group 2 and group 3), ANOVA is used. If ANOVA produces p<0.05, you would further like to know which of the following three pairs have 'honestly' significant differences:
  • group 1 vs group 2;
  • group 2 vs group 3;
  • group 1 vs group 3.

If you use t-test, there will be more false positives than expected as 1 ANOVA test now becomes 3 t-tests. For example, if alpha=0.05 is set for 1 ANOVA test, alpha will become 1-0.95*0.95*0.95=0.14 for 3 t-tests. This is commonly known as 'alpha inflation' in multiple comparisons.

To avoid 'alpha inflation' in multiple comparisons, Tukey's test is used to keep the alpha at the same level and therefore the results are "Honestly Significant Differences (HSD)". This online Tukey's HSD calculator gives explanations for some real data examples.
James White is offline  
November 30th, 2017, 07:27 AM   #3
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Why on the alpha level need to be keeped?
Thanks on your answer!!!
shaharhada is offline  
December 1st, 2017, 04:39 PM   #4
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Quote:
Originally Posted by shaharhada View Post
Why on the alpha level need to be keeped?
Thanks on your answer!!!
It is preferred to keep alpha at the same level (usually set at 0.05). Otherwise, people can get 'significant results' by simply making a large amount of comparisons.

This famous research study gives you a simple explanation:
Why Most Published Research Findings Are False
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