All Questions
Tagged with nonparametric wilcoxon-mann-whitney-test
176
questions
3
votes
0
answers
180
views
Semi-parametric approach: nonparametric test of residuals from linear mixed model
I want to know if this is a reasonable approach. I conducted the same experiment on two different species with small sample sizes (7-25 per species) in 4 years at 6 different sites. I measured damage ...
- 31
5
votes
2
answers
1k
views
Comparing P value from t test vs. Mann-Whitney test
If you analyze the same data with a t test and the nonparametric Mann-Whitney test, which do you expect to have the lower P value?
- 20.9k
4
votes
4
answers
10k
views
Which test to choose when the results from t-test and Wilcoxon test are different?
I have a sample of 48. According to the central limit theorem, I may consider means of every continuous variable in my sample to have a normal distribution.
However, one variable has a mean of 14 +/- ...
- 41
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
8
votes
1
answer
166
views
How to test that a set of distributions are located in a given order?
I have a set of population distributions; I obtained them empirically, computing histograms from very large populations (about 1 million per distribution). The population distributions might not have ...
- 199
0
votes
1
answer
6k
views
How to compute Wilcoxon rank-sum test in Stata?
I would like to compute the Wilcoxon rank-sum test in Stata for two countries of my sample with the dummyvalue 3 and 6.
Can anyone give the right code for Stata?
- 1
13
votes
3
answers
1k
views
What is the null hypothesis in the Mann-Whitney test?
Let $X_1$ be a random value from distribution 1 and let $X_2$ be a random value from distribution 2. I thought that the null hypothesis for the Mann-Whitney test was $P(X_1 < X_2) = P(X_2 < X_1)$...
- 3,288
8
votes
2
answers
2k
views
The exact distribution of Wilcoxon rank-sum statistic U
The distribition of the rank-sum statistic U is assumed to be normal for large number of samples being considered. What is the exact distribution? I want to compare and sometimes fuse results from ...
- 2,402
5
votes
1
answer
129
views
Should the group decisions be independent in Wilcoxon rank sum test?
In case you want to compare the average income of a group of male employees against the average income of a group of female employees, the observations are clearly independent.
Now, I have a network ...
- 53
16
votes
1
answer
4k
views
Why is the Mann–Whitney U test significant when the medians are equal?
I've received a results from a Mann-Whitney rank test that I don't understand.
The median of the 2 populations is identical (6.9). The uppper and lower quantiles of each population are:
6.64 & 7....
- 1,241
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