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Can at test be used with any size sample?
10 Answers. There is no minimum sample size for the t test to be valid other than it be large enough to calculate the test statistic. Validity requires that the assumptions for the test statistic hold approximately.
Can independent samples have different sample sizes?
Unequally sized groups are common in research and may be the result of simple randomization, planned differences in group size or study dropouts. Unequal sample sizes can lead to: Unequal variances between samples, which affects the assumption of equal variances in tests like ANOVA.
Can you compare samples of different sizes?
One way to compare the two different size data sets is to divide the large set into an N number of equal size sets. The comparison can be based on absolute sum of of difference. THis will measure how many sets from the Nset are in close match with the single 4 sample set.
When to use student’s t test instead of Welch’s?
There is a very specific set of effect size/sample size combination where Student’s t-test has a little (but not enough to make it worthwhile) more power. This is discussed in the literature, and since you cannot be certain you have equal variances in tiny samples, you should always report Welch’s t-test if you do science in the real world.
Is the Welch approximation t test the same as independent samples?
The Welch approximation t-test is designed to do the same thing as an independent samples t-test, but without relying on the assumption that the variances are equal. It is readily available in most standard statistical software.
What is the p-value of Welch’s t test?
Also, the two-tailed p-value of the test is 0.14, which is larger than 0.05 and confirms that the two population means are not statistically different. The following code illustrates how to perform Welch’s t-test for our two samples using the statistical programming language R:
Do you use Levene’s or Welch’s t test?
A widely recommended approach in textbooks where you first test the assumption that variances are equal with Levene’s test is a waste of time – just always use Welch’s t-test.