Questions tagged [wilcoxon-signed-rank]

a non-parametric rank test to compare two paired samples, whether values in one are bigger than in the other. This test is NOT the same as the sign test.

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Basic question regarding before and after intervention analysis on groups of different sample size

Apologies for the basic nature of this question. I have collected data before and after an intervention and assessed response to the intervention using a survey. This was a basic survey using a 1-5 ...
june2023's user avatar
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What do these Wilcoxon values tell me?

I did a pre and post-test with a small number of students ($n=12$).These values came after a science intervention that took $4$ weeks. I used a Wilcoxon test for 2 related samples as there was not a ...
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Wilcoxon test on distribution derived from bootstrapping

We have two Chocolate bags X and Y. Each chocolate bags have total 1000000 chocolate boxes randomly sampled from 100 types of chocolate boxes (B1, B2, …, B100). These chocolate boxes are of different ...
jayesh kumar's user avatar
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Paired t-test on dependent samples

I have a set of paired observations, corresponding to patient blood pressure before and after a treatment. I'd like to test for the significance of the treatment by conducting a paired t-test (or ...
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Kruskal-Wallis Test shows significance, but Pairwise Wilcoxon Rank Sum Test does not

I used the following code to perform a Kruskal-Wallis test on a dataset, which gave me a significant p-value (5.159e-06). However, when I then use pairwise.wilcox.test() to perform a Pairwise Wilcoxon ...
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simulate the number of samples to be statistic relevant using a non-paremetric paired test

I have an experiment where a group of subjects must learn to associate some sounds to images (say, sound 1-image 1, sound2-image 2,... soundN-imageN). They do a memory test (we present sounds and ...
user3284182's user avatar
3 votes
2 answers
219 views

Transitivity of Wilcoxon signed-rank test

I have performed Wilcoxon signed-rank tests for variables $X$, $Y$, and $Z$, where it appears that (speaking informally) $X < Y < Z$. Indeed, the p-value for the one-sided Wilcoxon signed-rank ...
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Multiple testing with Wilcoxon signed rank test with set maximum length

I'm essentially performing this test with the Java Apache math3 method which only allows lengths up to 30. My pairs will have a length of maximum 2048. I will be testing for an increase (combination ...
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investigation of a potential change of measured values: only the simple linear regression or also compare the mean of follow-up values with baseline?

For my medical dissertation I am studying a group of 36 patients. The patients received a drug repeatedly over several months. Serum levels of two cytokines were measured in the patients both before ...
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Validity of Wilcoxon Signed Rank or Spearman for 2 Likert Scales

I am working on my MSc dissertation findings and I have data results from two 5-Point Likert scales. One Likert measured self-assessed behaviour, whilst the other measured attitude. (Both scales were ...
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Test(s) for comparing predictor quality for different features?

I applied a predictor to different numeric features from the same group of subjects (n>1000). The features have different ranges. Is it possible in this case to apply a statistical test to make a ...
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Questions about Wilcoxon signed rank test

I wanted to conduct a Wilxocon signed rank test but stumbeld upon two questions that I am unable to solve on my own. I tested 2 types of interfaces for a software with the same ten people. I want to ...
Lukas Pezzei's user avatar
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Zero differences and Wilcoxon signed rank test

I am wondering if the Wilcoxon signed rank test is an appropriate test for my data, that does not follow a normal distribution. I have 150 datasheets of numbers of drugs measured at two points in time....
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Constant p-value for all my tests

I am comparing the performance of two AI models across 15 data sets. One model performs heavily better than the other on all the performance metrics. When I perform a one-tailed Wilcoxon signed rank ...
M Germanos's user avatar
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Two sample t-test vs One-sample t-test on residuals [closed]

For some arbitrary data, I have the raw data and a fitted model (not a regression model, but more so a model that accounts for noise and imperfections the data acquisition). I want to see how closely ...
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Analysing pre and post intervention MCQ results for significance- which statistical test to use?

I have ran a teaching course for students. I carried out pre and post session MCQ quizzes to evidence effectiveness of the course, however the marks collected were anonymised (data collected via ...
S Hussain's user avatar
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Calculation of standard deviation of the mean changes from the p-value or z-value of the Wilcoxon test

I am conducting a meta-analysis of observational studies without a control group that compared a parameter's value before and after an operation. All included studies have reported their results as ...
victor james's user avatar
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What exactly does the “symmetric distribution” assumption of the Wilcoxon signed-rank test refer to? [duplicate]

I have two lists (or sets) of data that I would like to statistically compare. More precisely, I would like to check if the difference between data list one and data list two is statistically ...
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Determining KAP assessment post-intervention significance: use a paired t-test, signed-rank Wilcoxon, or other?

I'm newer to statistics and unsure how to analyze my data for a cohort study (n=73) where KAP assessments were administered to the same pregnant women before and after an educational intervention for ...
ram_i_rez's user avatar
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Do I always have to consider all possible pairs in post-hoc pairwise comparison?

I performed an ANOVA on some test results of N groups (N = 7), which yielded a significant difference of the group means, followed by a wilcoxon signed-rank test to determine which groups are ...
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Study results showed that the posttest scores got lower than the pretest scores, yet wilcoxon results show that there is significant difference

We had a study on the effectiveness of a learning intervention. We collected pre and post test scores and the results showed us that the students' scores got lower in posttest than the pretest. But ...
Anne's user avatar
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Wilcoxon sign rank test in R does not match with GraphPad Prism

I am comparing several combinations of two columns of non-normally distributed paired data: I used R with the following syntax: wilcox.test(x, y, paired=T) I tried to replicate this test in GraphPad ...
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Is the Wilcoxon Signed Rank Test appropriate when the Brier score is the accuracy metric?

When comparing model performance, is it valid to use the Wilcoxon signed rank test for matched pairs, when the accuracy metric is the Brier score? (Here, the Brier score is used in calculating the OOB ...
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Assessing the Impact of a Specific Treatment on Survey Results: A Wilcoxon Signed-Rank Test Approach on Paired Samples

I have conducted a survey with several scale questions ranked 1-10 on a sample of n=18. I applied a specific treatment before and after the survey. However, I'm unsure about how to analyze the data ...
EI_Stats's user avatar
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Wilcoxon Rank Test Pre/Post By gender

I am trying to compare the paired pre to post-responses in a student survey to see if gender plays a role. I was told to do a wilcoxon signed ranked test, and I can get the mean and p-value by each ...
Cam's user avatar
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How to run Wilcoxon signed-rank test for pairwise comparison of two factors with three variables each?

I performed a study where I took 9 measurements from each participant for 2 factors (time/ location) and 3 variables each. These created the following combinations: T1L1, T1L2, T1L3, T2L1, T2L2, T2L3, ...
tarun14110's user avatar
1 vote
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How to analyse ordinal data for five food samples

I've conducted a questionnaire asking participants to rate biscuit samples based on factors such as taste and look. The ratings ranged from strongly like to strongly dislike. What is the best method ...
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Paired sign and Wilcoxon tests with weighting

In R, I am using the survey package (inverse probability weighting) to conduct these tests on paired data: Weighted Wilcoxon Signed Rank test Weighted Sign test However, I am struggling in doing ...
Matteo's user avatar
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Statistical test to compare models results for concordance index

I'm working on a model for survival prediction and using the concordance index to evaluate the results (https://medium.com/analytics-vidhya/concordance-index-72298c11eac7) . I want to show that my ...
coffecake8284's user avatar
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Test on significant difference

I need to test if there is a significant difference in leakage between prototypes. I've tried kruskal wallis and post hoc wilcoxon pairwise and Dunn-Bonferroni test, and the post hoc test always say ...
rklk sek's user avatar
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Why is the pseudomedian better than the median in a Wilcoxon test?

The wilcox.test function in R calculates the pseudomedian and a confidence interval when conf.int=TRUE. In this question, ...
kidokin's user avatar
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One Sample Wilcoxon effect size

I am struggling with effect size calculations for the Wilcoxon test for one sample in R. My data: item1 <- c(1,5,3,4,4,2,3,2,1,4,5,4,3,1) ...
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Dual choice experiment - Is the paired sample Wilcoxon signed rank test the most appropriate?

I conducted an experiment with insects to find out whether one odour is preferred over another. The insects had the option of moving towards one of the odours (one of the stimulus zones) or staying in ...
jaypeg's user avatar
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Statistical significance for REPEATED ordered categorical data

I have data of the following form: Rating 1 2 3 control 0 20 11 treatment 6 14 12 Where 1 is a plant of top quality, 2 is a plant of lesser quality that USED TO BE top quality, and 3 is a plant of ...
Wilhelm's user avatar
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Comparing standardised values of microbial colony perimeters

I’m having a statistical problem (a rather major one) and I was wondering if you could help. I’m researching microbial chemotaxis and analysing colony perimeters by scanning their fluorescence. ...
Cameron William Michael Murphy's user avatar
1 vote
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I'm having trouble choosing between Wilcoxon matched pairs test and McNemar test for a data set

I have a data set on a large group of long-term stroke survivors. I need to determine whether there is a difference in ability (on a scale of 1-10) between their left and right arms. The ordinal data ...
Harry_Fallows's user avatar
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Confidence intervals and significance for the one sample Wilcoxon test

I'm confused about the one sample Wilcoxon test returning significance for the following sample, when the null hypothesis is that the median equals zero (two sided test): ...
elcortegano's user avatar
2 votes
1 answer
237 views

Wilcoxon signed-rank test - the "distribution of differences is symmetric" assumption

How do you define "symmetric" here? In a paired test scenario, if one treatment consistently produces better outcome than the other treatment, I'd imagine the differences to be clustered on ...
mp6's user avatar
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3 votes
1 answer
885 views

Post-hoc tests after Friedman test

In Statistical Comparisons of Classifiers over Multiple Data Sets (p. 12) Janez Demsar suggests to use the Bonferroni-Dunn test as a post-hoc test after the null hypothesis of an initial Friedman test ...
user378615's user avatar
2 votes
2 answers
44 views

Why is p value different in same hypothesis? [closed]

wilcox.test(weight ~ group, data = my_data, paired = TRUE) wilcox.test(weight , group, data = my_data, paired = TRUE) can anyone specify the difference to me ...
none's user avatar
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is it necessary to meet all assumptions or does it matter for the multivariate regression?

...
none's user avatar
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What statistical test can be used to compare the accuracy of three different regression models which were applied on the same test data set?

I want to analyse how three different training data sets affect the accuracy of RandomForest regression models. I therefore train three models (one for each training data set) and apply them on the ...
LeonardoMxx's user avatar
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Friedman test_multiplicity

I'm performing Friedman test to see if there is a difference between 8 treatments, then if it is significant I'll do Wilcoxon signed rank test to see which pair is significant. I wonder if I should ...
user365345's user avatar
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One sample Wilcoxon Rank-Sum Test to compare percentiles

I have 10th, 25th, 50th, 75th and 90th percentiles of a population which is NOT normally distributed. On the other hand, I have a sample from that population and I want to test if its percentiles are ...
Hossein's user avatar
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4 votes
1 answer
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Creating a reference group to have equal sample sizes for Wilcoxon signed rank test

I am analyzing three years' worth of data. For some descriptive analysis, I want to know if there is a difference in the median between, $year_1$ and $year_2$ compared to $year_3$. To do this, I ...
Levi M's user avatar
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Wilcoxon or dependent t test for my work

Me and my colleagues were doing a interventional study regarding diabetes knowledge in patients (pre-post study) and we have used fasting blood sugar as the parameter .In the results part the ...
Dona's user avatar
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Can you accept the alternative hypothesis is the Wilcoxon rank sign test says to retain the null hypothesis?

All the tests that were carried out prior to WRS test shows to reject null hypothesis, but WRS test is saying to retain the null hypothesis. However, rejecting the null hypothesis makes more sence. Is ...
pragati's user avatar
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1 answer
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Calculating effect size of wilcoxon test after correction for multiple comparisons using R

I am trying to compare two amino acid concentrations after two treatment variations. The data is not normal distributed, so I have to use non-parametric tests. I calculated the adjusted p values, but ...
Mats's user avatar
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2 votes
1 answer
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Independence assumption of non-parametric tests (Mann-Whitney & Wilcoxon Signed rank)

I'm interested in testing (one at a time) these two hypotheses using the... Mann-Whitney U test. H0: The probability that an observation in Group1 is greater than an observation in Group2 is 0.50 But ...
Nate's user avatar
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Wilcoxon Signed-Rank Test N>300

There were similar questions here but as a person with little knowledge about statistics I couldn't understand any of it. I was looking for critical value tables that reached up to to higher amounts ...
Jamal Kareem's user avatar

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