Questions tagged [tukey-hsd]

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

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One of my groups (out of 3) doesn't have normal distribution, while a One-way Anova showed unequal variances (using SPSS); what to do?

I have an experiment where I'm testing the effect of a drug on behavior, measured in seconds. My drug group doesn't have normal distribution, probably because of a bimodal pattern: 6 of the 8 are ...
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0answers
331 views

Post-hoc test for randomization analysis

I've been experimenting with the coin package for doing the randomization equivalents of parametric tests. I've been trying to do a randomized version of an ANOVA ...
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1answer
891 views

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 ...
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71 views

Multiple testing correction for correlated test statistics

I have a matrix, the rows stand for the different diagnostic subgroups (6) and the columns stand for 4 different test statistics, making in total 24 values of test statistics. I should mention that ...
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0answers
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Will Tukey multiple comparison be the same for different types of Sum Of Squares of ANOVA for an unbalanced design

I am working on Two-Way ANOVA for an unbalanced design. Will Tukey multiple comparison be the same for different types (I, II & III) of Sum Of Squares of ANOVA for an unbalanced design. I am ...
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559 views

a priori power analysis for ANOVA plus post hoc test

I would like to perform an a priori power analysis to calculate required sample size for data to be analyzed using one way ANOVA and Tukey HSD post hoc test. (I want to determine pair-wise which ...
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0answers
682 views

Calculating Tukey HSD for a subset of comparisons - can I do this?

A colleague has about 50 samples, each with 2 conditions (treated and non-treated). The data is continuous and normal, and there are 3 data points in each sample-treatment combination. They'd like to ...
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1answer
64 views

Which R statistics tests to use in order to compare the effects of different variables on a test score

cross posted from StackOverflow I'm hoping someone can help point me in the right direction. I've got a data set which includes 'testscore', 'User Type (a or b)', 'Gender' and 'Age Group'. The data ...
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1answer
1k views

Interpretting non-contiguous significance letters from Tukey HSD test in the multcomp package? [closed]

I've only ever seen the compact letter display for Tukey's HSD give contiguous letter groupings but like in the following example this package is giving non-contiguous groupings (ie 'cde' is ...
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1answer
1k views

Same estimates but different p-values in tukey post hoc test (lmer)

I'm pretty new in using lmer and be confused about different p-values in Tukey post hoc tests associated with exactly the same estimates. I built a linear mixed ...
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0answers
181 views

Identify outlier in a group with a test statistic

I am trying to identify the outliers from a group for a research article. I wanted to know if there was a formal statistical method of doing so. Here is an example of the data: There are 500 students ...
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149 views

How does using Tukey's test correct for multiple comparison problem?

I am curious about the intuition behind the Tukey's HSD. I know that it is designed for post-hoc test(WHEN and HOW part), but I want to know underlying theory that justifies its usage(WHY part). To ...
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117 views

Multiple Comparisons Corrections within Subgroups

I've got a set of data points with "scores" that belong to a series of subgroups (not necessarily disjoint). That is, I may have a point that belongs to groups A, B, and D, and then another point that ...
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0answers
441 views

How to exclude unwanted comparisons in two-way ANOVA in R

I would like to know the way to exclude all the unwanted pairs of POST-HOC tests from the output generated from two-way ANOVA. Details as follows: I have datTable ...
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3answers
7k views

How to obtain Tukey Table in R?

The R provides a very confusing function for Tukey distribution. The function qtukey needs a nonsensical parameter nmeans which ...
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1answer
588 views

Tukey test in factorial experiment

Use Tukey's test to determine which levels of the pressure factor are significantly different for the data. I already did the anova table My question is when making comparisons in Tukey test,...
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1answer
757 views

How to perform ANOVA followed by a post-hoc for model comparison?

My data is the measurement of 4 type of samples with three different methods where I want to see the interaction and main effect, compare them from each other. The data look like as follows: ...
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1answer
5k views

Tukey's Test or LSD Fisher

I'm trying to solve the above exercise, but my question begins with which test should I choose: Tukey test or Fisher's LSD? I read several things and still can not tell the difference between the two ...
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1answer
270 views

How does number of treatments affect ANOVA/Tukey-HSD results?

My data contains 3 treatments: A (n = 10), B (n = 15) and C (n = 5). I run an ANOVA test and reject the null hypothesis, so I perform a Tukey-HSD post-hoc test and find that there is a significant ...
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1answer
670 views

criteria for choosing a post-hoc tests

After eg. ANOVA there are several post-hoc tests out there (e.g. Tukey, Bonferroni, etc.) but what are the criteria for choosing one over the other? If one is more conservative, shouldn't we use it ...
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1answer
348 views

transitive property in statistical comparisons

I want to know if the exposure to a given dose of a toxic chemical alters the concentration of a given substance in blood in my animals. I make this super general, bear with me, because I think this ...
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0answers
229 views

TukeyHSD for non-pairwise comparisons

Following this question: Pairwise comparisons I'm not sure if I can perform a Tukey Honest Significant Difference test on the data I have. I've thought Tukey's method was only valid for pairwise ...
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1answer
2k views

two-way multiple comparisons in R

This is a subset of my dataset: ...
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1answer
455 views

LDA, Tukey HSD: little questions from a chemist

As you may know, analytic methods like PCA or LDA are used everywhere in science. In my case, I'm a chemist, and I use it to differentiate molecules. I have 4 different systems (let's call them A, B, ...
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1answer
1k views

Nested mixed effects with lme4

I am trying to analyze data from an experiment using lme4. In the experiment, subjects saw either dark or bright versions of 50 stimuli (between-subjects; fixed effect "brightness"). All subjects saw ...
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0answers
864 views

interpreting multcompTs from multcompView in R

This graph was created using multcompBoxplot (from multcompView), and I'm having a difficult time interpreting what the mulcompTs of this graph are telling me in terms of differences between my ...
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1answer
632 views

Post hoc test for 1-way Anova with heteroscedasticity

I understand that post-hoc Tukey contrasts are inadequate on a 1-way ANOVA that violates the homoscedastiscity assumption, and that Games Howell or Dunnet contrasts are among the recommended ...
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2answers
2k views

Post hoc analysis for linear mixed model with nested effects

I'm having trouble in R with my Linear Mixed-Effects Model. I'm working with yeast in nectar. This is a part of my data just so you can see what is going on: For the condition sucrose, I have 4 ...
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1answer
4k views

Tukey's test on two way ANOVA

So I have done a two way ANOVA, and would like to do a post-hoc Tukey's HSD test. What should I use for the $k$, SE, degrees of freedom and what is my $q$ and HSD? The exp is done in 4 places with ...
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0answers
209 views

Multiple ANOVAs, then multiple Tukey HSDs, correcting for multiple comparisons

My experiment has 5 conditions (let's say Treatment A, B, C, D and E). There are 12 measurements (let's say Measurement 1-12). I'm running 12 ANOVAs on the measurements, I assume this means I should ...
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2answers
3k views

TukeyHSD multiple comparison on binomial data using Multcomp package in R

My question is how to perform TukeyHSD multiple comparison on ratio(for example, conversion rate, graduate school admit rate) using multcomp package in R. Take UCLA admission data for example: ...
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0answers
1k views

Tukey HSD, insignificant p-value when the confidence interval does not contain 0?

I am using TukeyHSD to do multiple comparisons. I am seeing strange results for some of the pairs: the adjusted p-value is greater than the specified significance level but the corresponding ...
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1answer
13k views

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 (...
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1answer
2k views

Tukey for GLM can't find data in model

I fit a GLM to a dataset. Now I want to see where the difference between my groups is, so I tried to run a Tukey HSD as a post-hoc test. Because of it is a GLM, I can't use ...
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1answer
316 views

what statistical test should i use for three groups with different sample sizes?

What statistical test should I use if I have three independent groups of interval data and would want to check whether their means are significantly different? I'd also note that the samples sizes of ...
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1answer
4k views

Post-hoc tests on linear mixed model give mixed results.‏

I am quite new to R so apologies if I fail to ask properly. I have done a test comparing bat species richness in five habitats as assessed by three methods. I used a linear mixed model in lme4 and got ...
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1answer
179 views

Should we conduct post-hoc tests when there is a significant interaction but no significant main effects?

I have data showing outcomes of some treatment on different people grouped by sex and age (grouped into: infant, child, adult). I need to investigate if there is any difference in outcome among age ...
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0answers
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Controlling for Type 1 Errors: Post-hoc testing on more than 1 ANOVA

I have conducted several repeated-measures ANOVA's with post-hoc testing via Tukey's HSD whenever the omnibus F-test was significant. I'm having some confusion about controlling for type 1 errors when ...
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1answer
3k views

Why is the Tukey confidence interval wider than the T-test confidence interval?

I have two confidence intervals for a comparison of two means. The first is a t-test CI and the other is a Tukey CI. The Tukey CI $(2.36, 26.5)$ is wider than the t-test CI $(6.46, 21.33)$. What is ...
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1answer
13k views

Are pairwise Wilcoxon tests a valid non-parametric alternative to Tukey's HSD test?

I am trying to identify significant differences between groups from normal and non-normal distributions. When the distribution is normal the workflow is pretty straightforward: ANOVA and after that a ...
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3answers
6k views

ANOVA shows no significant interaction effect, but Tukey's Test shows significant differences between groups?

I am a PhD student but I am having a hard time understanding certain aspects of statistics. I just ran an ANOVA and I got no significant interaction effect between Density (0 and 20) and Species (...
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2answers
3k views

Can you accept the alternative hypothesis if the global test is significant but the pairwise comparisons are not?

My hypothesis states that "there would be significant differences among a, b, c and d group on the X measure." I used ANOVA to see the group differences which came out to be significant. After that I ...
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0answers
619 views

Question about Tukey post-hoc ANOVA test results

I have used a Tukey post-hoc test after seeing that the ANOVA test indicated some significant differences between my groups (A,B,C,D). I am somewhat confused about the results. Why, for example, is A ...
2
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1answer
7k views

Significant ANOVA interaction but non-significant pairwise comparisons [duplicate]

I ran a two-way ANOVA and got a significant interaction. I ran a Tukey.HSD() post-hoc test in R and no pairwise comparisons were significant. Is this an error on my ...
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0answers
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Do only certain pairwise comparisons after significant interaction in two-way ANOVA

I am comparing measurements on a test group relative to a control group in three different environmental conditions. I am interested in both differences between environmental conditions and ...
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1answer
3k views

Non-orthogonal planned comparisons: How to correct alpha?

I have a data set containing three groups (A, B, C). Group A and Group B have undergone two different types of training designed to improve the same thing. Group C is my control group with no ...
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0answers
48 views

How to plot and analyze a simple grain yield trial?

I am looking for a common trial design for comparing 6 different sunflower cultivars, and a way to analyze it as a part of a course I am taking. The common know-how in my class is to set the trial in ...
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0answers
178 views

Comparing the mean of several exponentially distributed variables

(Possibly related to Is there a nonparametric equivalent of Tukey HSD?) Given a set of several exponentially distributed variables (representing data which is modeled this way), I'd like to check ...
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1answer
865 views

Outlier detection using Medial Rule

I have a data set captured every minute. Using Tukey's test for outlier detection (i.e., if number points above Q2+2.3IQR is above 10% of total distribution) then I mark the one minute window as ...
2
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1answer
3k views

How to estimate P-value from bootstrapped distributions?

I have three sets of distributions generated from the bootstrap method. Normally I would do ANOVA to see if all distribution are equal and then Tukey HSD to get confidence interval and P-value on ...