[R] t-statistic for independent samples

[David Arnold]

Hi,

Typical things you read when new to stats are cautions about using a
t-statistic when comparing independent samples. You are steered toward a
pooled test or welch's approximation of the degrees of freedom in order to
make the distribution a t-distribution. However, most texts give no
information why you have to do this.

So I thought I try a little experiment which is outlined here.

Distrubtion of differences of independent samples
<http://msemac.redwoods.edu/~darnold/math15/R/chapter11/DistributionForTwoIndependentSamplesPartII.html>  

As you can see in the above link, I see no evidence why you need a pooled or
Welch's in these images.

Anyone care to comment? Or should I put this on Stack Exchange?

D.




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