All Questions
15
questions
2
votes
0
answers
194
views
How to conduct a boostrapped or a permutation wilcoxon test (in R)
I have a total of 18 mice, 9 from Healthy group and 9 from Sick group. Since I have a very poor sample size I would like to use boostrapping or permutation test.
Is there a way to conduct a ...
- 579
1
vote
1
answer
2k
views
How to handle ties in pairwise wilcoxon rank-sum test?
I am willing run the wilcoxon rank sum test for different combination of variables, and using the base R code, I get a lot of warnings. The reason is that there are so many (about 30% of the whole ...
- 143
0
votes
0
answers
65
views
Wilcoxon Rank Sum Test appropriate?
I'm using Wilcoxon Rank Sum Test on my data and I'm wondering if there is a better alternative to use and eventually what post-hoc I could do on my data.
Context: The objective is to find the ...
- 113
1
vote
0
answers
189
views
quantile regression result different from Mann-Whitney U test
The results of the quantile regression and Mann-Whitney U test are very different. My sample size is 39. The quantile regression returns p-value of 0.83, while Mann-Whitney U test gives 0.33.
Why are ...
- 1,499
1
vote
1
answer
2k
views
P-value correction for multiple comparisons using Mann-Whitney test (using R)
I have one question regarding the adjusted p-value for multiple comparison using Mann-Whitney test.
The data structure that I am dealing with is something like this:
Two groups to compare: Group 1 vs ...
- 335
0
votes
1
answer
514
views
I need to use a Wilcox Sign Rank test with unequal sample sizes
I'm analyzing a before and after treatment of farm fields based on runoff from rainfall events. Over 6 different farm fields there were 136 water samples from before the treatment was installed and ...
6
votes
1
answer
1k
views
What is pseudomedian in R function `wilcox.test`?
On my journey to understand what pseudomedian is I tried to calculate it manually in R using definition from wikipedia. Calculated on my data I found that reported value of ...
- 175
28
votes
2
answers
19k
views
Non-parametric test if two samples are drawn from the same distribution
I would like to test the hypothesis that two samples are drawn from the same population, without making any assumptions about the distributions of the samples or the population. How should I do this?
...
- 467
3
votes
1
answer
5k
views
Mann-Whitney U test when only summary data (mean, sd, sample size) are available
When raw data is not available, which normally occurs when we obtain our data from different scientific papers, how is it possible to perform a Mann-Whitney analysis to test whether two samples are ...
- 473
3
votes
1
answer
738
views
non-parametric tests with significant difference in sample sizes
I have outcomes from a biological expt., where we have measured DNA lengths that has been affected.
For condition1, I have 11 observations (length of DNA) and for condition2 I have approx. 116000. I ...
- 421
5
votes
1
answer
12k
views
How to convert from Mann-Whitney U to Z (or other effect size)?
I'm looking at multiple studies. I do not have the original data. One study I'm looking at provides means, standard deviations, and Mann-Whitney $U$ values (with $p$). (How) can I convert from Mann-...
- 255
10
votes
1
answer
20k
views
How do I interpret the Mann-Whitney U when using R's formula interface
Say we have the following data:
...
- 2,657
2
votes
1
answer
997
views
Randomization Tests
The following data are mandible lengths (mm) of 10 male and 10 female golden jackals Canis aureus in the collection at the British Natural History Museum. The two samples are independent.
...
- 21
11
votes
2
answers
5k
views
Wilcoxon-Mann-Whitney critical values in R
I have noticed that when I try to find the critical values for the Mann-Whitney U using R, the values are always 1+critical value. For example, for $\alpha=.05, n = 10, m = 5$, the (two-tailed) ...
- 1,042
6
votes
2
answers
942
views
Subsets not significantly different but superset is
I have various clinical data on participants in a study. I'm looking at a continuous variable ("A") and a (binary) categorical variable (group) ("O"). I used a Wilcoxon test in R (the data are not ...
- 1,261