# Tagged Questions

The Kruskal-Wallis procedure is a nonparametric equivalent of one way analysis of variance, used for comparing the location of three or more groups; it extends the two sample Mann-Whitney-Wilcoxon procedure.

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### AUC is equivalent to a Mann-Whitney U-score, is the basic multiclass AUC related to the Kruskal-Wallis test statistic?

I've read that the area under the ROC curve is equivalent to a Mann-Whitney U-score. Is a multiclass AUC score (which averages the AUC scores for pairs of classes) related to the Kruskal-Wallis test ...
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### Difference Between ANOVA and Kruskal-Wallis test

I am learning R and have been experimenting with analysis of variance. I have been running both kruskal.test(depVar ~ indepVar, data=df) and ...
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### Differences between Dwass-Steel-Critchlow-Fligner and Mann-Whitney U-test for a post-hoc pairwise analysis

If you have one control and four groups of patients with a non-normal small sample size, there are differences in these tests for a post-hoc analysis after Kruskal-Wallis?
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### Power analysis for Kruskal-Wallis or Mann-Whitney U test using R?

Is it possible to perform a power analysis for the Kruskal-Wallis and Mann-Whitney U test? If yes, are there any R packages/functions that perform it?
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### Paired t-test, Kruskal-Wallis rank sum test and chisquare test. Which test should I choose?

I observed moth oviposition in orchard for 4 moths (400 clusters per week). The moth oviposit on leaf and apple. I want to compare the means between oviposit on leaf and apple. I suppose to use paired ...
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### Advantage of using ANOVA over a kruskal wallis test

This question is a follow on from this question - Correlation with non-normal distribution. An ANOVA explanation was given here - Correlation between vegetation and erosion - that could be applicable ...
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### Correlation with non-normal distribution

I want to find the correlation between a continous variable with a non normal distribution, positively skewed, and a categorical variable with 4 categories. The only test I can find that fits these ...
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### Kruskal Wallis test with high type 1 error

using this code ...
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### Can I use ANOVA on a small sample size test where only some of the groups are not normally distributed?

I have run an experiment for fertility among fruit fly hybrids. There are six groups that I need to compare for significance with one another. Sample sizes are not equal: the number of trials varies ...
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### Five different groups

We are running a study which investigates platelet aggregation changes during three trimesters of pregnancy and postnatal period. Then, we compare each of these phases to control non-pregnant women. ...
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### Test selection for group comparison

We are running a study which investigates platelet aggregation changes during three trimesters of pregnancy and postnatal period. Then, we compare each of these phases to control non-pregnant women. ...
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### Questioning my analysis choices!

Brief overview of my data: Data collected from 60 questions split into three categories; degree of agreement with pre-defined statements, personal experience of the issue, and demographics. The ...
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### ANOVA / Kruskal-Wallis: one of four groups has different distribution

I'm using Kruskal-Wallis to as a non-parametric ANOVA of a non-normal distribution. My understanding is that it assumes each group of the independent variable has the same shape. As it turns out, ...
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### ANOVA and Levene test problem (2)

I want to reword my previous question. I'm running ANOVA for 4 clusters to understand is there any difference between these clusters in terms of their reasons for travel. After I checked Levene ...
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### Analysis of Similarities (ANOSIM) versus Kruskal-Wallis

What is the difference between the two sets of statistic tests? Which is recommended for finding out if the difference between groups is more significant than within groups, for non-parametric ...
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### Difference between disease conditions by non-parametric ANOVA

I've the following simplified data as shown. ...
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### Ranks test problem

This is a questions I got for homework in test planning and variance analysis. I apologize in advance for the way my professor phrases things :D I would love to hear hints or tips on how to approach ...
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### Confusion related to kruskal wallis test

I have some confusion related to Kruskal wallis test. I have an example lets say X=[2 2 35 10 9 8 11 12]; Y=[1 1 1 2 2 2 2 2]; Y is the group variable Now when ...
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### Kruskal-Wallis test of groups with unequal sample sizes matlab

I can't seem to work out why I can't perform a 5 grouped Kruskal-Wallis test on unequal sample sizes in matlab. Any thoughts how to do this? Also as a post-hoc analyis using Wilcoxon Rank sum is this ...
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### Is ETA a good measure for computing the efect size between an ordinal and a nominal variable?

I have a nominal and an ordinal variable and I would like to look measure the association that is between the two. For now, I have done Chi-square test and non-parametric Kruskall-Wallis Test and I ...
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### which test to use if you only have summary statistics? (non-normal)

Here's the basic problem: visiters to our website were randomly put into one of 7 different groups, and we want to compare the activity of users in the different groups on a downstream site. The ...
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### Choosing post-hoc test after Kruskal-Wallis

I have a time series (five time steps) of samples from a population of the same ~60 individuals, each sample being a haphazardly chosen (i.e. not completely random) subset of the 60. The sample sizes ...
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### Disagreement between normality tests and histogram graphs

My data consist of compaction measurements from 3 different cell types (X,Y, and Z). My goal is to know whether there are "significant" differences between these measurements, so I have tested for: ...
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### Need to analyze: Unequal variances, Factorial Completer Randomized Design

I'm trying to analyze data that violates the assumptions of an ANOVA (homogeneity of variances), thus I think I have to conduct a non-parametric test. My study follows a factorial completely ...
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### Appropriateness of K-S test and Kruskal-Wallis for assessing medical data set

I am analyzing some stats for a paper I am writing. I have statistics help available through my faculty but am not there for a couple of months so hoping you can help out. n = 463, 2 patient groups( ...
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### Benjamini-Hochberg dependency assumptions justified?

I have a data set where I test for significant differences between three populations with respect to some 50 different variables. I do this using Kruskal-Wallis tests, on one hand, and by likelihood ...
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### Nonparametric alternative to ANOVA for testing the difference between several brand preferences

I have collected a data from about 200 customers on their brand preference of 5 international fast food chain shops. Each customer was asked to rank all the 5 brands from highest to lowest (5 for the ...
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### Test data for differences

I am trying to figure out the best way to test my data for differences in R. The data I have look like this: ...
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### Which result to choose when Kruskal-Wallis and Mann-Whitney seem to return contradicting results?

I have these groups where the values are responses to a 10-point Likert item: g1 <- c(10,9,10,9,10,8,9) g2 <- c(4,9,4,9,8,8,8) g3 <- c(9,7,9,4,8,9,10) ...
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### Do we need to report the median or the Mean when using a Kruskal-Wallis test?

I have two groups. There is a significant difference according to the KW test. But do I need to report the mean or median of the groups?
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### Contradicting p-values for Anova and Kruskal-Wallis on same data: Which is right?

I have a data file with task duration values for three groups, and I want to determine group effect on task duration (tasks were executed by individuals; each group had 7 different individuals; each ...
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### Estimating Diversity of operon types using HMMs across metagenomes: Mann-Whitney? Kruskal-Wallis? or other?

Question that seems complex but probably isn't. I'm comparing 10 metagenomes (http://en.wikipedia.org/wiki/Metagenomics), that are supposedly unrelated (they are 10 geographically separate ...
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### Significance level of kwallis2 test in Stata

I have a question concerning the use of the kwallis2 test in Stata. If looking at the multiple comparison output, I receive a probability and (NS) or (S). What does ...
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### Multiple comparisons process using Kruskal-Wallis, G-Test and corrections

I want to know if changing a button color has a positive effect on different measures (see the 4 measures below), using the following process: There's a default button, which is the fixed control ...
2k views

### What statistics should I use to compare percentages?

I am trying to see if there is a statistical significant difference between the amount of bycatch in 5 different types of gear used by fishermen. For each gear I have varying number of replicates as ...
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### Difference between post-hoc test after Kruskal-Wallis and Bonferroni corrected Mann-Whitney tests

I have some non Gaussian distributed variable and I need to check if there are significant differences between the values of this variable in 5 different groups. I have performed Kruskal-Wallis one ...
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### Reporting significance in Kruskal Wallis test

I performed the Kruskal-Wallis one-way ANOVA by ranks on five groups of data using Dataplot software. The software corrects for ties and uses Conover's procedure to do pairwise multiple comparisons. ...
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### Non-parametric test for unequal samples with subsequent post-hoc analysis?

Is it okay to perform a Kruskal-Wallis on four unequal samples? Further to this, is there a subsequent pair-wise post-hoc suitable for two unequal sample sizes?
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### How do you report Kruskal Wallis one way analysis of variance and post hoc results following APA 6th standards?

How do you report Kruskal Wallis One Way Anova and post hoc results according to APA (American Psychological Association) 6th ed. standards? I have tried to find a template for reporting the results ...
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### Is there a non-parametric test, like a Kruskal-Wallis, but with uneven blocks?

I have a continuous response variable, nominal independent, and want to block by site, though the numbers at sites are unequal. Is there any alternative to a permutation test? If not, does anyone know ...
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### Testing the difference of (some) quantile-Q between groups?

For some Y variable, that is divided into 3 groups (X), I wish to compare the groups and for the hypothesis that the 90% quantile is the same between all three groups. What tests can I use? One ...