All Questions
Tagged with nonparametric t-test
96
questions
6
votes
3
answers
351
views
T-tests provide info about the margin of mean difference?
I have 2 unpaired datasets where the difference of the sample means is quite substantial (with the naked eye). The t-test shows that the difference is significant (p-value=0.007) and I would like to ...
- 63
0
votes
1
answer
345
views
Interpret Mann–Whitney U Test with highly skewed data
I have data for ~102,000 hands of bananas. The dataset has four data points:
Spiders present (True/False)
Count of rotten bananas in hand
Count of total bananas in hand
Percent of bananas that are ...
- 245
1
vote
0
answers
134
views
Tests for positively skewed data with large enough samples?
I'm new to statistic tests so I need a little bit of help with them. Most of my data has distribution similar to the histogram below.
As it can be seen from the histogram, the data is positively ...
2
votes
2
answers
43
views
Is there a way to quantify how appropriate a t-test is for given data?
I'm doing some programming and analysis for a post-doc who used to do this workflow using Excel and StatPlus. Apparently StatPlus has some feature where you tell it to compare two samples, and it will ...
- 241
4
votes
1
answer
164
views
T-Test or U-Test
I have a number of items that are based on a Likert scale, with values ranging from 1 = not at all to 5 = very much so. I would like to compare answers to these questions between two groups. I would ...
- 125
0
votes
0
answers
311
views
Wilcoxon signed rank test or t-test if data is highly skewed?
I have an variable that is highly skewed and I want to test whether my mean is equal to some fix value in another population. I only have the arithmetic mean of the other population. Because I prefer ...
- 227
1
vote
0
answers
670
views
Mann-Whitney U Test and Independent t-test give different results, which to use?
I have two population and I want to know if the means of the two populations are different. To the best of my knowledge, I should try an Independent t-test if the data is normality distributed and ...
- 65
3
votes
1
answer
74
views
Best tests for significance of relative risk
Currently I have insurance claim loss data (say roughly N=10,000), with independent variables state (California, Washington, etc.), policy number (uniquely identifies a policyholder), type of car (...
- 237
1
vote
1
answer
81
views
Is there any possible statistical test for this data?
I have a data set of the daily dosage of a drug that participants take against some signs and symptoms. The data are highly skewed to the left because there are a lot of patients with 0mg per day of ...
- 29
1
vote
0
answers
286
views
Testing for normality with small sample sizes in order to use t-test [duplicate]
I run into a conundrum when determining whether a small sample is appropriate for a t-test. I know that if I meet the assumptions, a t-test produces approximately correct inference with any sample ...
- 497
2
votes
2
answers
134
views
Which version of the t-test (or other) should I use?
UPDATE: I added histrograms and qqplots at the bottom.
A dataset of 1500 scores is close to being normally distributed, but is somewhat pointy, and is right-skewed. It has a mean of 500, and a ...
user179810
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
2
votes
1
answer
2k
views
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)" ...
1
vote
0
answers
46
views
Paired t-test on large sample that *should* be normal, but isn't (or Wilcoxon Signed Rank Test)?
A dataset contains the number of fast food restaurants per thousand people for each county in the USA, for two different years (five years apart). 3,143 rows.
None of the following are normally ...
user252085
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