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.

Filter by
Sorted by
Tagged with
8
votes
1answer
3k views

Multiple comparisons with many groups

I would like to determine if using multiple comparisons test would be appropriate for my data. I used the Kruskal-Wallis test to determine if there were differences in mean inhibition among $17$ ...
3
votes
1answer
6k views

Bonferroni correction on multiple Kruskal-Wallis tests

My data consists of 3 groups, and 6 variables. The data are not normal so I want to use non-parametric tests to uncover significance. The first thing I wanted to get your opinion on is, is it ...
5
votes
1answer
378 views

Comparing classification results from models selected differently with Kruskal-Wallis

For a seminar at university I'm reviewing a paper that proposes a new feature selection algorithm. The authors also evaluated their algorithm by applying it beside two other feature selection ...
3
votes
1answer
761 views

Kruskal-Wallis and Ordinal Logistic Regression

Many relate Ordinal Logistic Regression (OLR) with Kruskal-Wallis (KW) in the sense that OLR may be used when there are two or more IVs and interaction effect between them are of interest, while KW ...
2
votes
0answers
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 ...
2
votes
1answer
788 views

Kruskal–Wallis non-parametric alternatives for groups with different shaped distributions

My question does't duplicate this question, even if the titles are nearly similar. The Kruskal–Wallis test "assume that the observations in each group come from populations with the same shape of ...
0
votes
1answer
1k views

Adjusting for multiple Kruskal-Wallis tests

I've run 3 different machine learning algorithms on 10 different datasets, generating an accuracy on each one. My hypothesis is that two of the algorithms are consistently better than the third. I've ...
12
votes
1answer
24k views

How to read the results of Dunn's test?

How do I read the results from Dunn's test? Specifically, what do the values in the table below tell me? I have non-parametric data in 4 groups, and I first did a Kruskal-Wallis test to confirm that ...
2
votes
1answer
475 views

Wrong Intepretation of Kruskal Wallis Test in R

I have some data (called egecNonmated) in R and I am trying to show that the distributions of a variable (MatchScore) are identical across three different Categories (Cat). I am using a box plot to ...
0
votes
0answers
1k views

Variance assumption and normal assumption not met, Kruskal or Welch-Anova?

I have 7 different groups of playing time data that is not normal. Lets say its really not normal..like a lot. The variance is also not equal and fails the bartlett test by a landslide. Sample ...
3
votes
1answer
1k views

How to implement ordinal logistic regression for a factorial design

I have read a few answers (e.g. this, this and this) recommending to use Ordinal Logistic Regression (OLR) as a generalized method when Kruskal-Wallis is not suitable. For instance, a 2x2 factorial ...
1
vote
1answer
336 views

What is a one-way ANOVA on the ranks of the observations

While reading this link: http://www.statsdirect.com/help/Default.htm#nonparametric_methods/kruskal_wallis.htm, I came across the following: ...
3
votes
2answers
2k views

Any other non-parametric alternative to Kruskal-Wallis?

It looks like Kruskal-Wallis is the standard nonparametric test for more than two groups. The problem is that it does not tell which groups are different, except that whether there exists significant ...
2
votes
1answer
130 views

What are the consequences of using ANOVA instead of Kruskal-Wallis on non-normally distributed data?

I am doing a high-school statistics assignment and am having trouble finding answer to this question. Anova and Kruskal-Wallis test are very confusing and I am lost trying to find and explanation to ...
0
votes
0answers
459 views

Rank sums in the Kruskal-Wallis output

I use Stata to perform a Kruskal-Wallis test on four groups of data (not normally distributed), and the results are shown below: ...
1
vote
1answer
106 views

Relationship between nominal and ranked variables

I am practicing statistics on the gss dataset. I want to study the relationship between people owning guns in the USA and political inclination. Owning guns or not is a nominal variable while ...
3
votes
1answer
1k views

Statistical significance test: One way Anova and Kruskal-Wallis test

I was comparing data between two groups and for each group there was six samples. My data are as follows: group 1: 103.56, 103.32, 103.32, 104.27, 103.56, 103.8 group 2: 97.16, 97.16, 96.69, 98.58, ...
3
votes
1answer
2k views

GLM post hoc with non-parametric tests?

I have a question regarding the appropriate use of comparisons for independent samples (3 factor levels). Overall sample size is N=546, subsamples: 218 or 228 or 100), convenience sampling, stratified....
1
vote
0answers
132 views

Which post-hoc comparison to use and why

Hopefully this is now a much clearer picture of the question I want to answer: For each of 60 different plans I ran 35 simulation replications of my Agent Based Model (ABM) simulation. Then for each ...
1
vote
1answer
464 views

Factorial design for interactions with ordinal DV

I want to make a 4 question, multiple choice survey in which each question asks about an analogous range of actions for slightly different scenarios. Each participant would only be administered the ...
4
votes
2answers
824 views

Why am I getting inconsistent results from Wilcoxon signed rank test and Kruskal-Wallis test?

I am doing a study on 3 drugs, comparing response pre-post treatment. My objective is to know if these drugs are effective and which one is better. I used non parametric tests since the results weren'...
9
votes
4answers
16k views

Can Mann-Whitney test be used for post-hoc comparisons after Kruskal-Wallis?

I have a simulation where an animal is placed in a hostile environment and timed to see how long it can survive using some approach to survival. There are three approaches it can use to survive. I ran ...
1
vote
0answers
39 views

Comparing transaction counts between samples

I have a treatment group and two control groups for customers and the count of their transactions: ...
2
votes
1answer
2k views

Kruskal-Wallis and Dunn's

I am trying to interpret the results of some experiments I have run, involving showing participants videos of animated synthesised speech. I ran a mean opinion score test. I made 36 movies in total. ...
2
votes
0answers
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 ...
1
vote
0answers
879 views

Repeated measure two-way ANOVA (non-parametric)

Non-parametric ANOVA – a hot topic that is unanswered. There are many questions on this topic online. However, they all seem to end in a debate and no definite answer or clear explanation (that I ...
1
vote
1answer
40 views

Independent Variable groups w/ n=1 possible for Kruskal Wallis?

I am working with clinical data with 7 groups that constitute my independent variable and a not normally distributed dependent variable. I know I have to use KW test to check for significant ...
3
votes
2answers
3k views

Kruskal-Wallis test is not significant but some of the Mann-Whitney comparisons are significant

I have a non-normalized dependent variable and an independent variable broken down into 4 groups. As such, I used the Kruskal–Wallis analysis to look for significant differences in the ranks of the ...
11
votes
1answer
9k views

Multiple comparisons in a non-parametric test

I am working with a data set that is non-parametric and has 12 treatments. I performed the Kruskal-Wallis test and got a significant $p$-value, and now I would like to conduct a multiple comparisons ...
1
vote
0answers
162 views

Kruskal-Wallis test for factorial design [duplicate]

Is it possible to use the Kruskal-Wallis test for two factors and their interaction (i.e., two way ANOVA: Y~a*b)? And which post-hoc test is possible to use after ...
2
votes
2answers
953 views

Kruskal-Wallis?

I have three sets of data (1 set before treatment, second during treatment and the third after), each of which consists of hundreds of trials on a specific task that involves choosing 1 from 7 ...
5
votes
3answers
464 views

Similarity of time series

I try to find out the smallest window size for calculating statistical values on a stream. To illustrate my problem: I record the average car counts per brand on a street using different sliding ...
3
votes
0answers
2k views

Interpret the pairwise comparison plot from SPSS [closed]

For my user study, I am trying to find out to what extent people prefer to move by foot. They had the option to rank their preference for 'walking', 'jogging' and 'running' for a several amount of ...
1
vote
0answers
34 views

Comparing reaction tests

I have an experiment where every person needs to take reaction tests when he/she is sober, then when lightly and then heavily intoxicated. I need to perform a test that tells if the intoxication had ...
0
votes
1answer
364 views

Alternative to Friedman test for single treatments (no repetitions)

I'm looking for a non-parametric (!) alternative to the Friedman test. I have > 2 subjects and measured one quantity per subject. I want to know whether there is a significant difference between any ...
2
votes
1answer
2k views

Kruskal-Wallis Test and Mann-Whitney U Test

I have a three samples of data where each has a non-normal distribution: I want to determine whether the samples differ. Therefore I apply the KW test and it gives me a significant value, i.e. the ...
2
votes
1answer
3k views

Mean ranks and standard errors of Kruskal-Wallis test

While it's easy to compute the p-value of Krsukal-Wallis non-parametric test using the kruskal.test() function, I don't know how to compute the mean ranks and ...
5
votes
1answer
11k 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 ...
0
votes
0answers
132 views

Are very low ANOVA and Kruskal Wallis p-values reason to doubt the results?

I have four relatively small sets of data under five different conditions. For each set of data I want to see whether the differences between the conditions are statistically significant. The first ...
3
votes
2answers
36k views

How to report Kruskal-Wallis test?

As part of the analysis of the data collected from a survey, I was carrying out Kruskal-Wallis Tests between some Likert scale questions and demographics such as firm size and job position. I am using ...
2
votes
2answers
93 views

Influence of two factors on non-normal outcome. Which test?

I measured two variables (outcomes) $Y_a$ and $Y_b$ for several subjects. $Y_a$ and $Y_b$ are continuous variables defined on $[0,100]$ and have a bimodal distribution. I tried using a transformation ...
3
votes
1answer
951 views

Non-normal distribution even with Kruskal-Wallis test

Thanks to anyone who can help! I`ve done a survey with Likert-scale questions with about 1,500 participants. Initial analysis in SPSS showed no outliers (using box-plot) but scores were not normally ...
20
votes
4answers
42k views

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 ...
5
votes
1answer
5k views

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?
13
votes
1answer
9k views

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?
0
votes
1answer
2k views

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 ...
0
votes
0answers
792 views

Correlation with non-normal distribution [duplicate]

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 ...
4
votes
1answer
721 views

Kruskal Wallis test with high type 1 error

using this code ...
2
votes
1answer
81 views

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. ...
1
vote
0answers
50 views

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. ...