All Questions
Tagged with nonparametric t-test
96
questions
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1
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56
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Very small degrees of freedom when using yuen function in WRS2 package of R
I'm trying to run a number of independent samples t-tests. I'm using the yuen function in the WRS2 package because my data are non-normal and ordinal. My sample ...
- 13
3
votes
1
answer
692
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I have applied many statistical tests to my data, but still cannot determine normality
I have run multiple tests to determine normality on my dataset, but I am unsure which one to adhere to, especially since my histograms, density plots, and QQ plots leave much to be desired in terms of ...
- 53
3
votes
1
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130
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If I have a very small n for one group and a very large number of features, should I choose a parametric or a non-parametric test?
I have a dataset that contains human metabolite concetration in a fluid. One group has about 12 samples, while another only has 5. My question is if I can assume normality for this data and do ANOVA/t-...
1
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0
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44
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Which Non-Parametric Test should I use?
I want to make sure I am choosing the right statistical test.
I am working with 7 semesters of exams scores for a particular course.
Each semester the course ran with many sections. However, the ...
- 11
2
votes
1
answer
494
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Wilcoxon signed-rank test with an additional covariate
Problem formulation
I have 5 strains on which I administered treatment and repeated the experiment two times independently. So my data looks something like this:
...
- 165
0
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0
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86
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Which statistical Test should I use/ Comparing 2 groups
I am new to statistics, can someone guide me regarding the test I should use to compare the foot dimensions of 9 subjects to footwear dimensions (we have 2 footwear brands).
So, to simplify, I have ...
1
vote
2
answers
82
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Are t-tests good choices here?
I would like to test if two groups of participants (dark-eyed and light-eyed individuals) respond to a drug differently over time. The hypothesis is that the drug reaches its peak effects sooner but ...
- 13
2
votes
2
answers
292
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Justification for conducting independent samples t test on non normal data
I've conducted a study comparing two different teaching strategies in two different sections of the same class; I gave participants in both classes the same 5 tests and wanted to see if test grades in ...
- 21
1
vote
1
answer
574
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Welch's t test vs Mann-Whitney for very unequal groups
I have two vastly unequal groups (n1=18 and n2=400), and want to test mean differences between the groups for some 700 parameters (more specifically, RNA expression levels for 700 genes).
While I ...
- 33
0
votes
0
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80
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Self-contradictory asumption of normality? Nonparametric point-biseral correltion coeffiicent? t-test or Mann-Whitney U?
A. I know from the net that for a design with one binary variable and a second variable that is continuous but is NOT normally distributed, I can use BOTH the point-biserial correlation (which is ...
- 1,363
2
votes
1
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138
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How does violation of normality conditions affect p-values (relative to permutation tests)
I am running some t-tests using data from small samples (n=25) whose distributions do not appear to be normally distributed (they are not extremely skewed, but the skew is apparent in the plots and ...
0
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0
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39
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Appropriate test for two not-normally-distributed data samples
I have some data comparing training participants who experienced the same training course either face-to-face or virtually (via Zoom). I have two survey items I am comparing. Sample A is for virtual ...
0
votes
1
answer
1k
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Effect size for Welch's t-test
I ran an independent sample t-test to compare two groups, student sample and Mturk respondents. The homogeniety of variance was not met (variances are not equal and sample sizes of the two groups are ...
- 1
2
votes
2
answers
337
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Concept Clarification: Wilcoxon rank test vs two-samples T-test (UPDATE)
I am currently deciding whether to use the Wilcoxon rank test vs two-samples T-test to assess BMI between two unrelated groups. Using the following code to assess normality ...
- 361
0
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0
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64
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Wilcoxon or T-test, paired, or unpaired? large data set, almost 1/2 are zeroes for habitat suitability values
Background I am just learning how to work with Spatial Distribution Models, these are basically regressions on environmental values and occurrence coordinates for a species. The result is a grid map ...
- 1