All Questions
Tagged with nonparametric hypothesis-testing
308
questions
140
votes
8
answers
121k
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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
77
votes
15
answers
12k
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Why would parametric statistics ever be preferred over nonparametric?
Can someone explain to me why would anyone choose a parametric over a nonparametric statistical method for hypothesis testing or regression analysis?
In my mind, it's like going for rafting and ...
- 947
52
votes
3
answers
51k
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Bootstrap vs. permutation hypothesis testing
There are several popular resampling techniques, which are often used in practice, such as bootstrapping, permutation test, jackknife, etc. There are numerous articles & books discuss these ...
- 2,957
32
votes
2
answers
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StackExchange fires a moderator, and now in response hundreds of moderators resign: is the increase in resignations statistically significant?
I am doing a study on StackExchange. The management of StackExchange has demodded (for unclear reasons) a moderator, and now the network is on fire.
Currently many moderators resign or suspend their ...
- 82.3k
28
votes
2
answers
19k
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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?
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- 467
24
votes
5
answers
13k
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What exactly does a non-parametric test accomplish & What do you do with the results?
I have a feeling this may have been asked elsewhere, but not really with the type of basic description I need. I know non-parametric relies on the median instead of the mean to compare... something. ...
- 315
22
votes
7
answers
2k
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Isn't it problematic to look at the data to decide to use a parametric vs. non-parametric test?
I've seen in some instances of people mentioning that using a parametric vs. non-parametric approach may be decided by looking at the data. For example this question: nonparametric vs. parametric
Isn'...
- 243
22
votes
1
answer
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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
20
votes
3
answers
3k
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When to check model assumptions
Statistical methods are based on model assumptions. For example, an independent one-way ANOVA makes the following assumptions:
Normally distributed residuals
Homogeneity of variance
Independence of ...
- 301
19
votes
3
answers
2k
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Statistical test for two distributions where only 5-number summary is known?
I have two distributions where only the 5-number summary (minimum, 1st quartile, median, 3rd quartile, maximum) and sample size are known. Contrary to the question here, not all data points are ...
- 1,095
18
votes
5
answers
5k
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Checking ANOVA assumptions
A few months ago I posted a question about homoscedasticity tests in R on SO, and Ian Fellows answered that (I'll paraphrase his answer very loosely):
Homoscedasticity tests are not a good tool ...
- 2,211
18
votes
5
answers
25k
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Is logistic regression a non-parametric test?
I recently received the following question via email. I'll post an answer below, but I was interested to hear what others thought.
Would you call logistic regression a non-parametric test? My ...
- 45.5k
15
votes
5
answers
16k
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How to test an interaction effect with a non-parametric test (e.g. a permutation test)?
I have two categorical / nominal variables. Each of them can take only two distinct values (so, I have 4 combinations in total).
Each combination of values comes with a set of numerical values. So, I ...
- 622
13
votes
2
answers
2k
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If any parametric test does not reject null, does its nonparametric alternative do the same?
If nonparametric tests are assumed to have less power than their parametric alternatives, does this imply that if any parametric test does not reject null, then its nonparametric alternative does not ...
- 3,989
13
votes
1
answer
12k
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Friedman test vs Wilcoxon test
I'm trying to assess performance of a supervised machine learning classification algorithm. The observations fall into nominal classes (2 for the time being, however I'd like to generalize this to ...
- 233