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November 24th, 2017, 08:05 AM  #1 
Senior Member Joined: Nov 2011 Posts: 174 Thanks: 2  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. 
November 29th, 2017, 11:41 AM  #2 
Newbie Joined: Oct 2017 From: US Posts: 13 Thanks: 1 
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:
If you use ttest, there will be more false positives than expected as 1 ANOVA test now becomes 3 ttests. For example, if alpha=0.05 is set for 1 ANOVA test, alpha will become 10.95*0.95*0.95=0.14 for 3 ttests. 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. 
November 30th, 2017, 07:27 AM  #3 
Senior Member Joined: Nov 2011 Posts: 174 Thanks: 2 
Why on the alpha level need to be keeped? Thanks on your answer!!! 
December 1st, 2017, 04:39 PM  #4  
Newbie Joined: Oct 2017 From: US Posts: 13 Thanks: 1  Quote:
This famous research study gives you a simple explanation: Why Most Published Research Findings Are False  

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