All Questions
20
questions
3
votes
1
answer
131
views
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
vote
0
answers
44
views
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
0
votes
0
answers
87
views
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
views
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
1
vote
1
answer
582
views
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
2
votes
1
answer
138
views
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 ...
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
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
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
1
vote
0
answers
36
views
2 sample t test
I was thinking that a simple 2 sample t test is not that simple when dealing with skewed data.
Considere 2 samples, each one with diferent skewness and kurtosis, both with a big sample sizes (say n > ...
- 561
1
vote
2
answers
696
views
Under what circumstances does Mann-Whitney and Wilcoxon signed-rank test fail?
I read from here that
The advice must be modified somewhat when the distributions are both strongly skewed and very discrete, such as Likert scale items where most of the observations are in one of ...
- 1,041
1
vote
0
answers
45
views
Non parametric tests for relation/association between variable
What could be an appropriate test for checking whether there exist any relationship between Net Promoter Score ( Categorical in nature with 0 meaning detractor, 1 meaning Neutral, 2 meaning Promter ) ...
- 111
2
votes
0
answers
455
views
Effectiveness of exam: did it achieve the goal?
I have a dataset of student scores in an exam. Its structure is as follows:
...
- 121
1
vote
3
answers
2k
views
Using t-test/ANOVA on bounded data
Can a t-test/ANOVA approach to hypothesis testing be carried out when data has well-defined upper and lower limits and is not continuous?
Let's assume a situation where data are generated by some ...
- 11
0
votes
0
answers
838
views
Comparing means between two groups if dependent variable is a percentage
I have data on recovery rates from several hospitals across the country. The recovery rates are in percentages.
I want to compare the mean recovery rate between two groups of hospitals, one that uses ...
- 1