The wilcoxon tag has no wiki summary.
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1answer
48 views
how to analyze pre-post attitudinal data (ordinal) collected from a group of 60 students?
I have a survey with 25 items that were administered pre and post an intervention. Each item had four possible responses: (1) Not Appealing at all; (2) Not Appealing; (3) Somewhat Appealing; and (4) ...
2
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1answer
82 views
When is it appropriate to use a paired Wilcoxon test?
Could someone please explain in plain English (preferably without using the word paired) or by using examples when it is appropriate to use ...
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0answers
76 views
Comparing max/min over several time points against baseline
I have a time-series dataset with repeated measurements (multiple subjects). I have around 100 variables to test. The question is - Is something happen in a time range independently on exact time? For ...
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0answers
197 views
How to report results from Friedman's test including post-hoc results
I have performed comparison of repeated measures for a group using Friedman’s test (K-related-samples test) and additional post-hoc analysis with Wilcoxon signed-rank test and Bonferroni correction. I ...
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3answers
163 views
When sample size is small and distribution is not normal should I use Wilcoxon or T-test or something else?
I have two sets of data and need to compare mean times for a variety of situations (i.e. time of day, day of the week, different areas, etc...). Some of the situations have small samples sizes (n=8) ...
2
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1answer
114 views
Wilcoxon matched pairs test for my dataset?
I really hope someone can help me as i have been reading about this stuff and i am still really confused!
I have a dataset of 180 chemical compounds with 2 data (numerical) values each - i want to ...
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0answers
131 views
Wilcoxon-Mann-Whitney Output
I proposed a question early on infection rate data in 6 different hospitals for two years (N=12). After speaking with several people I decided that a Wilcoxon-Mann-Whitney (Mann-Whitney U, Wilcoxon ...
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0answers
57 views
significance test to use for multiple conversions in an A/B test
What is the proper way to measure significance in an A/B test, when a visitor can potentially "convert" more than once?
I understand a chi-square test or z-test are most often used for A/B testing, ...
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1answer
71 views
Can I use RM ANOVA instead of Friedman
I am currently analysing my quantitative data. My sample size is 157 students who sat for a survey in 2 phases after an intervention. The same students sat for the same survey on positive outcomes on ...
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1answer
343 views
Is ordinal or interval data required for the Wilcoxon signed rank test?
Having looked at multiple online sources, I can't seem to get a straight answer. Could someone please clarify for me if ordinal data is sufficient to use for the WSRT and if not, is the sign test an ...
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3answers
81 views
Significant differences and related variables
I am reading a paper in which a statistical difference has been found between two treatment groups for a variable A (p=.05), but not for variables B (p=.06) and C(p=.06), even though A=B-C. Is this ...
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1answer
344 views
T-test or Wilcoxon signed rank or Mann–Whitney U
A magazine wants to know if the online viewers are more than its printed copy buyers.
Which statistics test is the best to use, the t-test or Wilcoxon signed rank or Mann–Whitney U?
If I have ...
0
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1answer
120 views
What paired test should I use and how do I interpret it?
The question:
The data file contains observations of the wavelengths (in nanometers) of
the main color in two kinds of shoe polish. (Sample size = 100). Are the wavelengths significantly different?
...
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0answers
131 views
Non parameteric tests for 2*2 mixed design
I have 2*2 mixed design, where the two factors are time and group. The time levels are pre- and post-intervention, and the group levels are control and intervention.
If I were using a parameteric ...
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2answers
72 views
What would be the most appropriate significance test for my scenario?
I have three groups of users $-$ $G1$, $G2$ and $Control$. The users in each of these three groups are different but are carefully selected and have similar properties. I treat each group with a ...
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0answers
152 views
Is the Wilcoxon paired rank test appropriate for this data?
I have two vectors of normalized data values representing two paired conditions ("methylation" and "expression"). A scatterplot of my data looks like this:
I'd like to know if I am using the ...
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0answers
275 views
In R, why are results different for 1-tailed wilcoxsign_test, wilcox_test, and wilcox.exact with paired data?
I am trying to determine why I am getting different results with these different Wilcoxson test implementations in R version 2.15.2. I have paired data with some ties. I have read the response for ...
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1answer
711 views
Output of one-tailed Wilcoxon sign rank test in R
I'm trying to assess the difference between two algorithms. They are stochastic, so I've run them multiple times against the same input files and noted their results. I want to determine whether my ...
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1answer
407 views
Using Student or Wilcoxon test on small sample without information on the normality of distribution
I have three subjects in a qualitative study. I am comparing the features of their writing before and after treatment.
I have no idea about the normality of the distribution since they were selected ...
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1answer
223 views
Is there a statistical significance in my paired sample data after performing Wilcoxon signed rank test?
I have a paired data consisting of $N$ = 421 samples. I would like to find out if there is statistical significance between the paired samples. Since, I do not know the underlying data distribution I ...
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1answer
100 views
Wilcoxon signed rank statistic
It seems there are two formulas to perform a wilcoxon signed rank test - one where the sum of all the signed ranks is w and another where the minimum of the sum of the negative ranks and positive ...
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1answer
52 views
What is the correct test to check whether a observable has changed after modifying a condition?
I run the following 'experiment':
take measurement x of observable
change one parameter
take measurement y of observable again
I do this many times and want to test whether changing the parameter ...
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0answers
45 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 ...
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1answer
130 views
Comparing continuous predictors for a dichotomous variable
I have two continuous predictor variables to predict a dichotomous variable. In addition i have constructed two (interaction) models, based on domain knowledge which use both variables to predict the ...
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1answer
1k views
Which W to report for the Wilcoxon test?
Imagine that I have the following data:
GroupA <- c(2,4,3,1,2,3,3,2,3,1)
GroupB <- c(3,5,4,2,4,3,5,5,3,2)
Then when I call in R
...
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4answers
1k 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 +/- ...
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2answers
375 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) ...
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2answers
87 views
Which test to use for comparing changes in computer source code?
I am not sure which test I have to use to analyze my data. The situation is as follows:
I have two computer programs which are doing exactly the same. Both share a large amount of source code, but ...
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1answer
577 views
What is the difference between wilcox.test and wilcox_test in R
These two functions exist in R but I don't know their differences. It seems that they only return the same p-values when calling wilcox.test with ...
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1answer
93 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 ...
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2answers
1k views
How to determine the effect size of a Wilcoxon rank-sum test in R?
I want to determine if there's a difference in mean p-values between two groups. In order to do this I perform a Wilcoxon's rank-sum test (the data is not normally distributed). So far, so good. ...
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3answers
367 views
How to find out if an online poker-site is fair?
Last week I had an interesting discussion with a good friend of mine. He had been playing some online poker and suggested that there is a relationship between new subscription/additional money ...
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0answers
169 views
Comparing means and variance of one group in two conditions
Probably a trivial questions, but I've been wrapping my head around it for a while...
I have a small sample (N=7) that performed a test in two conditions. No assumption can be made about the ...
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1answer
247 views
Bootstrap p.value, Wilcoxon rank sum or other test?
Imagine I have a network, and in this network I have n nodes of interest.
I calculated the average shortest path between these nodes.
I want to see if they are statistically significantly close to ...
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1answer
2k 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?
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1answer
828 views
How to perform a Wilcoxon signed rank test for survival data in R?
Say you have survival data like this:
...
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1answer
452 views
How do you calculate the effect size of one-sample Wilcoxon signed-rank test?
Can you / how do you calculate the effect of a one-sample Wilcoxon signed-rank test?
Is there a way to perform the calculation in SPSS or another software package?
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2answers
4k views
When to use the Wilcoxon rank-sum test instead of the unpaired t-test?
This is a followup question to what Frank Harrell wrote here:
In my experience the required sample size for the t distribution to be
accurate is often larger than the sample size at hand. The ...
2
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1answer
522 views
What are the assumptions (and H0) for Wilcoxon signed-rank test?
I am working on the assumption page of the Wilcoxon signed-rank test (the wilcox "paired test") in Wikipedia.
I was able to locate a reference for the assumption that I wrote there, which are:
Let ...
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2answers
2k views
How to test for differences between two group means when the data is not normally distributed?
I'll eliminate all the biological details and experiments and quote just the problem at hand and what I have done statistically. I would like to know if its right, and if not, how to proceed. If the ...
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1answer
1k views
How to compute the power of Wilcoxon test?
I am using Wilcoxon test to compare two paired sets of data for whether their means differ. Besides the p-value, I would also like to know the power of this test. How to compute it in R? Thank you in ...
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1answer
1k views
Please help me interpret these Wilcoxon signed-rank test results
I have 4 sets of data points and for each I want to see how much these values vary from zero.
I used the tool for calculating the results of the test on this page but I'm having trouble understanding ...
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2answers
989 views
How to do a paired test when some cases have no pair?
I have a question regarding paired and unpaired tests. I know the difference between both tests. I am using R for Wilcoxon test. My test is a paired test, however the X and Y do not have the same ...
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2answers
496 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 ...
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1answer
88 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 ...
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5answers
398 views
Logistic regression and Wilcoxon test
I ran a multivariate logistic regression with glm in R with some continuous and some categorical variables. Only continuous ...
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4answers
1k views
What's the difference between bootstrapping t-test and just using a nonparametric test?
I want to perform a single-tail test on a single sample of real numbers (N~100) against an expected value. The population is known to be not normally distributed. So from what I've read about stats, I ...
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2answers
282 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 ...
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1answer
538 views
Alternative to the Wilcoxon test when the distribution isn't continuous?
One of the assumptions for using the Wilcoxon sign-rank test is that the underlying distribution is continuous (see here.)
However, there are cases (for example, when analyzing Likert scale data) ...
