Questions tagged [kruskal-wallis]

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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multiple Kruskal-Wallis instead of ANOVA for non-normally distributed data

Apologies in advanced if I supply too little or vague information, since I am a complete newbie in stats and using this forum. So I did a study which evaluated psychopathic personality traits, ...
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6k views

How many « degrees of freedom » should a Wilcoxon rank-sum test have?

I would like to perform a Mann-Whitney U Test (also called Wilcoxon rank-sum test) on a weighted sample in R. Such a non-parametric test is required, as neither of the two variables used follow normal ...
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2answers
600 views

Kruskal Wallis or Manova

I have to analyse 8 independent variables (IV) toward 8 dependent variables (DV) in my research. The IV is nominal while DV are ordinal (likert-scale). I run the normality test and the result is zero (...
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6k views

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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178 views

ANOVA with post hoc for non-normal data with unequal variance

I have 200-some variables with 25,000 observations in each of 4 categories. For each variable individually, I need to identify where we have variability between categories. Therefore, I need an ...
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47 views

Is Kruskal-Wallis the right test?

I'm writing a research protocol and trying to work out the right test. Is there a significant difference between the success rate (dependent variable, ratio data) for different repair materials (...
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588 views

Mann Whitney U test or Kruskall-Wallis + Dunn test as a post hoc?

I performed a set of inhibition experiments where Lactobacilli supernatants where tested against a pathogen cell culture. These experiments were carried out in a 96-well plate where pathogen was ...
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127 views

Is it appropriate to apply ordinal regression to a continuous response “as is” (with no ties)?

The goal is to run non-parametric general linear model with no restrictions on the design (e.g. not limited to one-way ANOVA as in Kruskal-Wallis test; quantitative factors should be admissible, etc) ...
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4k views

Kruskal-Wallis test + Nemenyi post-hoc test: further multiple hypothesis correction needed?

I have used a Kruskal-Wallis test in a one-factorial design with samples that do not meet the assumptions for one-way ANOVA. To do this I have used the function ...
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600 views

Percentages from non binomial data: is ANOVA / Kruskal-Wallis appropriate?

I know ANOVA with percentages as already been discussed (Using ANOVA on percentages?) and (ANOVA-like test for bounded variables (percentages)), but the variables seemed different from my case. ...
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2k views

adjusting ties for kruskal.wallis

I would like to compare the means of three groups using the Kruskal Wallis test in R. My data looks like this: ...
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125 views

Is it okay to convert binary data to percentage data?

I have a within-groups study with 4 groups (400+ users). Each user answered 10 questions for each group. The answers were scored as right/wrong (1/0). Can the percentage correct for each user/group be ...
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177 views

Multiple Sample Equality-of-Distributions Test For Panel Data

Suppose I have repeated time observations for 800 meter sprint for a group of athletes over the course of a season. I would like to test the hypothesis that all the times are drawn from the same ...
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889 views

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 ...
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15 views

Why several studies change logical paired/unpaired assumption from omnibus to post-hoc?

There are several studies of highly-referenced researchers where a paired post-hoc test (e.g. Wilcoxon signed-rank) follows the omnibus unpaired test (e.g. Kruskal-Wallis): From Huang et. al "THE ...
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1answer
54 views

Effect size calculation for Kruskal-Wallis mean rank test

I have a published paper in which I'm attempting to calculate the effect sizes for various outcomes. For a pre-post scale, the authors report the sample size, mean rank, and p-value for an outcome (...
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32 views

Comparing 3 groups at 2 time periods

I'm analysing a dataset and comparing three zones at two points in time. The data in question is: Hourly sightings of wild fish (CPUE) In one of three adjacent zones (A, B, and C) During the ...
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47 views

Can I use both parametric and non-parametric tests?

I have 3 variables, A1, A2 and A3 A1 is temperature A2 is month A3 is location A2 has 2 months - March and May. A3 has 2 cities - Chennai and Dubai. My data is ...
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2k views

Wilcoxon Rank Sum test unequal sample sizes

I am comparing two sets of data using the Wilcoxon Rank Sum test. Although the distributions appear to be quite different, the p-value is quite high (0.344). This is the line of code being used for ...
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34 views

Significance testing on two groups (distributions) of many binomial distributions

Basically I have two (or more) different success probability generating distributions. In other words, there are two (or more) different (non-normal) distributions, which realize success probabilities ...
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46 views

For my data, should I use a Kruskal Wallis or one-way ANOVA test?

I read through some literature online and did some investigating on my data and the type of scales my data represents. In my data set, I have my independent variable called ASA status (this is a ...
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58 views

Kruskal Wallis H test

I am doing a Kruskal Wallis H test, it looks like I am getting a significant difference between the non-vegetarian group and the vegan group. But not with the semi-vegetarian group and vegan group. ...
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1answer
437 views

Two-Way Non-Parametric Test for Non-normal Data?

I have an unbalanced design with two factors, gender and site. I'm trying to test for differences in a size variable. Levene's test reveals that the data has equal variances. However, log transformed ...
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24 views

Non parametric tests for relation/association between variable

What could be an appropriate test for checking whether there exist any relationship between Net Promoter Score ( Categorical in nature with 0 meaning detractor, 1 meaning Neutral, 2 meaning Promter ) ...
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Is it ok to re categorize my variables this way?

I have a 2^3 factorial design, where the dependent variable is binary, and the three independents are binary and I care about interactions. I've seen that you can use logistic regression, but I feel ...
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59 views

Statistical tests, when data are not normally distributed & variance is not equal

I have a data with two variables - one variable is quantitative, and one is nominal (4 categories). I ran the normality tests and it turned out that this quantitative variable is not normally ...
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14 views

Comparing 4 groups of unequal sizes and non-normal distribution

I have 4 groups of students. Each student was asked to give us the number of reports they wrote through the semester.The 4 groups have n ranging from 5 to 250 ...
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1k views

Is it possible to use a Kruskal-Wallis test with multiple independent variables?

For my study, I'm investigating whether student's scores in a task (expressed as a percentage between 0-100%) influence their responses to a survey. The survey has 19 questions, and they're Likert ...
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112 views

Kruskal-Wallis test for showing features can discriminate the classes

I'm working on a problem for classifying 3 gestures using the EMG signals obtained from muscles. Each of the gestures has 6 trials of around 6-7s duration. Each trial is divided into multiple ...
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27 views

Collaborator pushing for robust sandwich estimator - is it appropriate?

I have a dataset that is survival data for 3 different treatments, single time point data (ie: % survived at end of treatment), with an n=10*3 for each treatment. This data is non-parametric, which I ...
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119 views

Is it appropriate to use Kruskal-Wallis test for one comparison and Wilcoxon Signed Rank Test for another?

I have a data set that I would like to perform several tests on to see if there are significant changes over time. I have replicated measures of 3 experimental ponds and 1 control pond that I have ...
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125 views

Kruskal wallis test for small dataset in R

I'm trying to test if there are systematic differences in a balanced data.frame composed by 25 observations of 3 variables: ...
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48 views

Discarding Brown Forsythe if homogeneity of variance in population has been shown in other dataset?

For the analysis of my experiment I used 2 one-way ANOVA tests. Both datasets were acquired from the exact same samples (and therefore population). They are merely two different parameters acquired. ...
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Proper name for the variant of Haldane estimator for handling empty cell in a 2xn contingency table

I am using R and survey package to analyse a survey that several 2xn contingency tables need to be analysed using Chi square ...
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494 views

Does Dunn Test require multiple comparisons correction?

If I compared 8 groups with a single Kruskal-Wallis test and it came back positive (<0.05), and then was interested in conducting a Dunn Test to determine which pairs differed between each other, ...
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22 views

Test for Statistical Differences Among GLM Modeled Data

I have three independent data groups - the groups are comprised of census tracts. Each data point (tract) within each group has a modeled estimate of disease prevalence (% pop that is obese as an ...
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419 views

Dunn-Bonferroni: All three differ significantly?

I have this huge knot in my head while writing my thesis atm. I am totally untalented when it comes to statistics, so it could be that my question is easy to answer for some of you. I did a Kruskal-...
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513 views

Comparing count data from multiple groups, Kruskal-Wallis with Dunn post-hoc or GLM with Poisson distribution?

Stats novice. I am comparing counts of microplastic artefacts from multiple independent sites, my null hypothesis is that there is no difference in counts between the sites. So far I have tried ...
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62 views

Post Hoc Kruskal - Wallis test for compare mean ranks

Can I use multiple comparison (Post Hoc Test) if Kruskal - Wallis Test can only be used to compare mean ranks?
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67 views

Testing for difference between count data where there are missing values (i.e. 0 in some cells)

I have collected data on different bumblebee species visiting a particular species of flowers over the course of the day. Counts were made every 10 minutes for 6 hours. I have now put all of my data ...
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481 views

How to read the result of of posthoc kruskal dunn test?

How to read the result of of posthoc kruskal dunn test? Specifically, what do the values in the table below tell me? I have 6 treatments and I first did a Kruskal-Wallis test to confirm that the ...
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195 views

Kruskal Wallis test for repeated measures

How do you perform the Kruskal Wallis test with 2 repetitions for the same patients? I have applied it on the difference of scores but what happened if there are more than two repetitions?
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75 views

How to calculate the Sample Variance for the Kruskal Wallis Test (with Ties)

The ranks are: Rank Group 1: 13, 15.5, 18, 21.5, 9.5 Rank Group 2: 4.5, 11.5, 18, 20, 18, 6.5 Rank Group 3: 3, 21.5, 11.5, 9.5, 15.5, 14 Rank Group 4: 6.5, 8, 2, 4.5, 1 So the means of ranks are:...
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116 views

Multiple comparisons and power analysis

I would like to compare 4 different groups for 10 different variables (the biodistribution of a material in different organs). Someone suggested me to use a Kruskal-Wallis test with Dunn's post-hoc ...
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426 views

Maximum number of groups in Kruskal Wallis one-way analysis of variance

Is there a maximum number of groups in Kruskal Wallis' one-way ANOVA? I am looking at a data set with 42 separate groups and I am unsure if there would be some sort of issue in running that many ...
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73 views

Mann-Whitney or K-W?

I am studying a biomarker in cancer, and I want to know if there are differences related with the location of the cancer (head and neck, lung or cervix). When I do the Kruskall-Wallis test, I find a ...
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126 views

Nested Anova with count (frequency) data

I have a data set that includes count data (# of times a behavior is observed, 4 total behaviors) that has been recorded at 2 research sites, and on multiple individuals at each site. I'm looking for ...
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47 views

Choosing the right test for cell count data and categorical data

I have recorded data from a lot of cells viewed under a microscope, and am now stuck trying to do a useful analysis of it. I have two types of cells (genotype; WT and null), and I treated them with ...
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43 views

Can I use the Kruskal-Wallis test for measures on the same animal before and after a treatment has been applied

In my experiment I have 3 treatment groups. Behaviours are scored for each subject (while they are isolated) before and after the treatment is applied. I thought that the Kruskal-Wallis test could ...
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36 views

What tests would be suitable for a survey with mixed question types?

I have done a survey (n=138) on student preferences of homework types. It's my first time attempting anything of the sort and I have a high schooler's understanding of math and statistics. My null ...