Episode #125 of the Stack Overflow podcast is here. We talk Tilde Club and mechanical keyboards. Listen now

# 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.

289 questions
Filter by
Sorted by
Tagged with
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 ...
13 views

### 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 ...
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 ...
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. ...
82 views

### 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 ...
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
16 views

### 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- ...
60 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. ...
12 views

### 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 ...
1k views

### 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 ...
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 ...
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 ) ...
20 views

### 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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 (...
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 ...
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 ...
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
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 ...
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 ...
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: ...
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 ...
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: ...
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. ...
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 ...
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 ...
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 ...
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 ...
2k views

### 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 ...
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 ...
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, ...
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' ...