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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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26 views

Is my analysis approach and decision valid?

I'm busy with a class assignment and I would appreciate a second pair of eyes on my analysis approach. A part of me feels that I'm overthinking this or have done an unnecessary test. Context: Use 4 ...
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Find joint distribution for two different cases Kruskal Wallis

I'm a bit stuck with my homework in a subject called "Non-parametric Statistics". The task is related to Kruskal-Wallis test. The task is as follows: Let's look at the comparison of 3 independent ...
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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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160 views

Is it okay to use non-parametric tests on normalized data?

I'm doing experiments with 3 conditions: A, B, and C. I have done the experiment 3 times, so each condition gets 3 values for a total of 9 values. Each value is actually an average of 5 measurements. ...
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multiple comparison with controls - kruskall wallis or mann whitney + bonferroni

I have a test group and two control groups. I would like to compare: test vs control group 1 test vs control group 2 and I don't need the result from control group 1 vs group 2. Therefore, in this ...
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716 views

Is it possible to calculate a confidence interval related to a significant p value from the kruskal wallis test?

I have run the nonparametric Kruskal Wallis test with pairwise comparisons in SPSS to understand if my 3 groups of survey participants were different in their responses to a range of 5 point ordinal ...
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2answers
2k views

Wilcoxon Rank Sum test unequal sample sizes [duplicate]

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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35 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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1answer
322 views

how to measure the correlation between non-normally distributed numeric variable and nominal variable?

I have two nominal variables and some numeric variables. The first nominal variable is a binary one. I want to measure the correlation between this binary variable and the other numeric variables. ...
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47 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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1answer
142 views

Are the results of my paired tests false positive?

I am dealing with a strange situation which I hope you can come up with a solution. I have 3 pared group(n=7 for each) which I tried to see if they are significantly difference and if so, in which ...
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133 views

Test statistic for follow up procedure (stepwise step down) of Kruskal Wallis

When conducting a Kruskall Wallis test, it is possible to follow up the procedure with a post hoc test, looking for homogeneous subsets. My question is which statistic is used to perform this ...
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What is the appropiate Non-parametric test for study with 3 conditions?

The IV has 3 separate conditions & the DV measures Pre & post scores (ultimately to see what condition has the biggest effect on the scores - if there is any). The data is non-parametric- ...
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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
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Accounting for measurement Bias across manufacturers and multiple treatments

I've been trying to figure out the appropriate statistical approach for the following problem from work (simplified here): I've got 5 manufacturers of a drug and each manufacturer makes their own ...
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Understanding hypothesis testing (Kruskal Wallis, Mann-Whitney) when there are tied values

tldr: In Python's Scipy stats modules, the kruskal and mannwhitneyu functions will both raise an error if called with only ...
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1answer
506 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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1answer
487 views

About Kruskal-Wallis, Mann-Whitney U and multiple comparisons correction

I have 5 independent samples which I want to compare, to define if there are significant differences in the distribution of values across samples. The samples' sizes are: 4562, 1116, 314, 151, 77 I ...
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1answer
227 views

Kruskal-Wallis and non significant post hoc test

I am running Kruskal-Wallis tests in SPSS to compare answers to Likert items among 3 (variable 1) and 4 (variable 2) groups. I am not running ANOVAs because assumptions of normality and ...
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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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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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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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48 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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87 views

Parametric vs non parametric tests for Likert items?

I have conducted a survey and am now trying to figure out how to analyse the results. I have a series of 6-point Likert items, which I have coded like this: -3 Strongly disagree -2 Disagree -1 ...
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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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1answer
500 views

Kruskal-Wallis vs Jonckheere-Terpstra Test

If we're doing a Jonckheere-Terpstra Test and a Kruskal-Wallis test at the same significance level, which one is more likely to reject the null hypothesis when it is actually true? From my ...
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895 views

Why is the Kruskal Wallis test statistic approximately chi-square distributed?

According to Wikipedia, the Kruskal-Wallis test statistic H is approximately Chi Square distributed under the null hypothesis. However I can’t find any resources explaining why that’s the case. I’m ...
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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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32 views

Which has more power Kruskal Wallis or Cox regression?

I am analysing behavioural data that is the latency for predators to consume prey within a ten minute trial. The data are not normally distributed, and I originally analysed them using Kruskal Wallis. ...
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2answers
306 views

Friedman's test or Kruskal-Wallis?

I am investigating the effect of an intervention treatment on a group of samples over 5 time points (a period of 2 months in total) For example: Subject 1 - Timepoint 1 (Dose 1), 2 (Dose 1), 3 (Dose ...
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86 views

Is it appropriate to remove meaningless pairwise comparisons from a post-hoc analysis before correcting for multiple comparisons?

I have four individual groups with two controls and two interventions. The second control group is specifically related to the first the intervention group, making the comparison to the second ...
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1answer
60 views

Can I run one way ANOVA at each of my time points?

Suppose that I have two or more groups of data (e.g. two or more cities with 10 sampled population each) and I want to test if they behave differently for a variable (e.g. specific crime) through the ...
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1answer
174 views

How to report statistically non-significant post hoc test after a statistically significant K-W test?

I conducted a Kruskal-Wallis test and the results were statistically significant. However, after conducting posthoc tests and calculating adjusted p-values for the test of mean difference between ...
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121 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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1k views

Kruskal-Wallis test: how to calculate the exact p-value?

I would like to calculate the exact p-value of a Kruskal-Wallis test. How can I do it? Is it a huge computational task? Imagine I have something like that: ...
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1answer
297 views

Is the Anderson-Darling test similar to the Kruskal-Wallis test to compare more than 2 groups?

I would like to compare more than 2 groups (their dependent variable is not distributed normally). Can I use the Anderson-Darling test like I would use the Kruskal-Wallis test? I have no specific ...
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132 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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49 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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1answer
115 views

Can Kruskal-Wallis be applied in this case?

In my experiment, I follow up 3 different groups of embryos for 12 timepoints. Each group has about a 100 embryos and I calculate the frequency (continuous variable) for each and tabulate the data for ...
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16 views

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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1answer
346 views

Problem with Dunn's post hoc test to compare a lot of groups?

I have a dataset were people sampled litter at 12 different locations. As the data does not have homogeneous variances I performed a Kruskal Wallis rank sum test (which came up significant) and ...
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2answers
1k views

Post hoc for Kruskal-Wallis Test

What post hoc test can I do after Kruskal-Wallis? Is there a post hoc test for non-parametric test? Some says there's none. I ran Kruskal-Wallis test and as a result the null hypothesis was ...
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Normality of distribution: Shapiro-Wilk and Levene tests

I have Likert-scale data from an experiment with 5 conditions, each of which has a different treatment and one is a control group. The goal is to compare the effect of the treatment between the ...
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133 views

Statistical test for data where groups have non-normal distributions with varying distribution shapes

I have between-subject design with 3 different groups where I capture interval data (on scale 1-4 where equal spacing amongst scores can be assumed). The data in groups is not normally distributed ...
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512 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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2answers
2k views

Wilcoxon-signed rank vs Kruskal-Wallis?

I am rather stressed out about my methodology. For my PhD I ran a year long literacy intervention (small scale longitudinal study) that was supposed to test the rate of change in individual students' ...
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1answer
30 views

Are different activities done by the same person independent or dependent variables?

I have 4-point ordinal data on users' opinions about various apps which they use, and I want to run significance tests on the ratings given to each app. None of the apps requires the others to be ...
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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 ...