All Questions
Tagged with nonparametric t-test
19
questions
140
votes
8
answers
121k
views
How to choose between t-test or non-parametric test e.g. Wilcoxon in small samples
Certain hypotheses can be tested using Student's t-test (maybe using Welch's correction for unequal variances in the two-sample case), or by a non-parametric test like the Wilcoxon paired signed rank ...
- 23.8k
63
votes
7
answers
54k
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Which permutation test implementation in R to use instead of t-tests (paired and non-paired)?
I have data from an experiment that I analyzed using t-tests. The dependent variable is interval scaled and the data are either unpaired (i.e., 2 groups) or paired (i.e., within-subjects).
E.g. (...
- 14.3k
7
votes
4
answers
9k
views
Should I use t-test on highly skewed and discrete data?
I have samples from a highly skewed dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want to compare their mean. For that, I'm using ...
- 551
2
votes
1
answer
2k
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Which statistical analysis should I perform if the data sets are not normally distributed?
I am doing an experiment where there are two independent groups; one is the group of "infected" patients another is the group of "sepsis" patients. I am comparing "platelet monocyte aggregates(PMA)" ...
22
votes
1
answer
43k
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Should I use t-test on highly skewed data ? Scientific proof, please?
I have samples from a highly skewed (looking like an exponential distribution) dataset about users' participation (e.g.: number of posts), that have different sizes (but not less than 200) and I want ...
- 551
1
vote
1
answer
722
views
How to find the difference between two set of scores of a single participant?
What I am trying to do?
I have a data set which consists of only one undergraduate student's all courses scores. Let's assume, he has completed about 70 courses where 40 courses are related to ...
- 294
7
votes
2
answers
12k
views
Non-Parametric altervative to one sample t-test
I have a the following hypothesis: $H_0: \mu=4$, $H_1: \mu\neq 4$, which I wanted to test using a one sample t-test.
However, my data is not normally distributed and a transformation was not found. ...
- 486
5
votes
2
answers
178
views
Wilcoxon (WMWU) test sensitivity
Statistics courses often give the Wilcoxon-Mann-Whitney U test ("Wilcoxon" from now on) as an alternative to the two-sample t-test.
However, the test is not quite the test of medians that would be so ...
- 65k
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
8
votes
3
answers
46k
views
What is a minimum sample size for a paired t-test and what is a non-parametric equivalent if data is non-normal?
I have 4 sample pairs, let's say (x1, y1),...,(x4, y4).
What is the minimum sample size for a paired t-test?
Which assumption should I check for paired t-test?
If my data is non-normal, what is an ...
- 1,284
7
votes
3
answers
9k
views
Non-parametric alternative to simple t-test
I have five numeric variables of two populations (each of them with 60 individuals) and for each of those five variables I want to know if there is difference in the means.
I was trying to use a ...
6
votes
1
answer
3k
views
What differentiates the wilcoxon test from t test regarding ordinal variables?
I'm wondering what the wilcoxon test differentiates from the t test so it can be used with ordinal variables. In other words why can't we use a t test for ordinal variables but can we use a wilcoxon ...
- 753
4
votes
2
answers
2k
views
Student's t vs Mann-Whitney U
I want to see if there is any difference in the number of dangerous permissions requested by free vs paid apps in Android store. I have equal sample sizes of 1900. When I plot the data they are both ...
- 41
4
votes
1
answer
915
views
How to analyze random variables with non normal distribution
I'm wondering how random variables can be analyzed using parametric methods if the distribution is not normal.
For example if a variable Y is normal distributed but I'm interested only on values Y2 ...
- 1,059
3
votes
2
answers
2k
views
Mann-Whitney for non-normal distributions with n>20?
I have 12 groups of datasets (mostly non-Normal, quite right-skewed), and I would like to see if there is a significant difference within each pair. (But the data itself is not a paired dataset, as in ...
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