Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [tukey-hsd-test]

Tukeys Honest Significant Difference (HSD) is a multiple comparison method based on the studentized range distribution.

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Comparing levels of factors after a GLM in R

Here is a little background about my situation: my data refer to the number of prey successfully eaten by a predator. As the number of prey is limited (25 available) in each trial, I had a column "Sample" representing the number of available prey…
Anne
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Is there a nonparametric equivalent of Tukey HSD?

I am using JMP to examine differences in vegetation cover in growth form groups (trees, shrubs, forbs, etc.) before and after three treatments with a control. My sample size is small (n=5) and most of my distributions are not normally…
UncleDJ
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Bonferroni or Tukey? When does the number of comparisons become large?

Reading Field's Discovering Statistics Using SPSS (3rd Edition) I was struck by a bit about post-hoc tests in ANOVA. For those wanting to control the Type I error rate he suggests Bonferroni or Tukey and says (p. 374): Bonferroni has more power…
Parbury
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How can I get a significant overall ANOVA but no significant pairwise differences with Tukey's procedure?

I performed with R an ANOVA and I got significant differences. However when checking which pairs were significantly different using the Tukey's procedure I did not get any of them. How can this be possible? Here is the code: fit5_snow<- lm(Response…
L_T
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How do you write up Tukey post-hoc findings?

What is the proper way to write a Tukey post-hoc result? There are several examples with different results? Say you have North, South, East and West. North N=50 Mean=2.45 SD=3.9 std error=.577 LB=1.29 UB=3.62 South N=40 Mean=2.54 SD=3.8 std…
Sue
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How to obtain the results of a Tukey HSD post-hoc test in a table showing grouped pairs?

I would love to perform a TukeyHSD post-hoc test after my two-way Anova with R, obtaining a table containing the sorted pairs grouped by significant difference. (Sorry about the wording, I'm still new with statistics.) I would like to have something…
stragu
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Box plot notches vs. Tukey-Kramer interval

The "notch" help document (or original text) from boxplot in 'R' gives the following: If the notches of two plots do not overlap this is ‘strong evidence’ that the two medians differ (Chambers et al, 1983, p. 62). See boxplot.stats for the…
EngrStudent
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When to correct p-values in multiple comparisons?

I'm afraid that related questions didn't answer mine. We evaluate the performances of >2 classifiers (machine learning). Our Null hypothesis is that performances do not differ. We perform parametric (ANOVA) and non-parametric (Friedman) tests to…
Chris
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Two-sample $t$-test vs Tukey's method

Even if the $F$ statistic in an ANOVA test is significant, we may need to do further testing before drawing conclusions. The most common method for doing this involves the use of a multiple comparisons procedure. I am trying to understand why…
user782220
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How could a Tukey HSD test be more signif then the uncorrected P value of t.test?

I came by the post "Post-hoc Pairwise Comparisons of Two-way ANOVA" (responding to this post), which shows the following: dataTwoWayComparisons <-…
Tal Galili
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Interpreting TukeyHSD output in R

I performed a simple ANOVA in R and then generated the following TukeyHSD() comparisons of means: I have a pretty good idea (I think) of what all this means except the 'p adj'. If I'm correct: The difference in test scores between say Juniors and…
Randy Minder
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Post-hoc test after 2-factor repeated measures ANOVA in R?

I have problems finding a solution regarding how to run a post-hoc test (Tukey HSD) after a 2-factor (both within-subjects) repeated-measures ANOVA in R. For the ANOVA, I've used the aov -function: summary(aov(dv ~ x1 * x2 + Error(subject/(x1*x2)),…
Jonna
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Meaning of “post hoc” multiple comparisons

My original thought was “post hoc” in a post hoc multiple comparison procedure means that the procedure is taken after an omnibus test (such as ANOVA F test) gives a significant result. But after reading Howell's Statistical Methods for Psychology,…
Tim
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Is a post-hoc test supposed to be performed on transformed or original data?

This might be a silly question, but I could not find an equivalent one on CrossValidated. I was wondering: if I transform my data in order to meet the assumption of homoscedasticity before running a two-way ANOVA, should I also use the transformed…
stragu
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ANOVA results do not match post-hoc Tukey test, how to proceed?

There has been some discussion about why differences exist between factor significance after an ANOVA and no significance in the pairwise comparisons, and it has been very helpful. However, there is no directions regarding how to proceed. For…
olia
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