# Linked Questions

1answer
816 views

### When should one use the Welch's T-test? [duplicate]

I want to test whether the mean in two samples are different. I don't know their variance and estimate them from the sample. When should I use the Welch-Satterthwaite approximation to the degrees of ...
0answers
105 views

### Welch t-test: Exactly when should it be used? [duplicate]

The guidance on this site concerning when to use the Welch t-test is somewhat general in nature (When conducting a t-test why would one prefer to assume (or test for) equal variances rather than ...
7answers
75k 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 ...
8answers
19k views

### How to test hypothesis of no group differences?

Imagine you have a study with two groups (e.g., males and females) looking at a numeric dependent variable (e.g., intelligence test scores) and you have the hypothesis that there are no group ...
4answers
9k views

### Practically speaking, how do people handle ANOVA when the data doesn't quite meet assumptions?

This isn't a strictly stats question--I can read all the textbooks about ANOVA assumptions--I'm trying to figure out how actual working analysts handle data that doesn't quite meet the assumptions. I'...
4answers
7k views

### Robust t-test for mean

I am trying to test the null $E[X] = 0$, against the local alternative $E[X] > 0$, for a random variable $X$, subject to mild to medium skew and kurtosis of the random variable. Following ...
3answers
726 views

### Choosing a statistical test based on the outcome of another (e.g. normality)

So I have heard it said that it is not a good idea to choose one statistical test based on the outcome of another. This seems strange to me though. For example, people often choose to use a non ...
4answers
4k views

### Both t-test and F-test are significant, do I report both?

I undertook a large study (N about 200 in both control and treatment) in which one of the user ratings is significantly different (p < 0.0001). When I ran the unpaired t-test, the F-test also ...
2answers
3k views

### What exactly does scipy.stats.ttest_ind test?

From the description: "This is a two-sided test for the null hypothesis that 2 independent samples have identical average (expected) values." Taken literally, this seems to be saying that we're ...
1answer
408 views

### How does the Welch correction for the t-test make the test non-parametric?

In an answer to another question it is asserted that the Welch correction to the t-test makes it non-parametric, and this assertion isn't challenged by a frequent contributor with a deep level of ...
1answer
428 views

### When to test for homoscedasticity?

Under what condition(s) do I need to test for homoscedasticity (i.e. using the Levene's test)? Is this only for repeated-measure designs or do I need to test for this in independent designs as well?