all of this discussion re: t test and normality and when it makes a
difference and when it does not ... plus all the other assumptions made in
all kinds of tests with similar sometimes/sometimes not problems ...
just reinforces the fact that we need to be real skeptical about p values
...
Bob Hayden wrote:
> In addition to the approximation involved in using the CLT, most
> (possibly all) practical situations require that you estimate the
> population standard deviation with the sample standard deviation in
> calculating a standard error for use in constructing a confidence
> inter
Some Monte Carlos I've done suggest that when the population is
distinctly skewed, the distribution of t is distinctly different from that
of Student's t, even when the sample size is large enough for the
distribution of sample means to be approximately normal.
Don Burrill in a discussion of the assumptions of t-test assumptions writes:
> "Acceptable" I don't know about: depends on the universe of discourse.
> But you should try to justify the assumption that the observations are
> taken independently, and that the underlying within-group variances a
Selections from an earlier exchange on EdStat-L are followed by some
comments.
- Forwarded message from Donald Burrill -
On Sat, 5 Aug 2000, Gates, Christopher [OMP] wrote:
> Donald, thank you so much for your response. I had the opportunity to
> converse with my friend (HOH) on this
On Sat, 5 Aug 2000, Gates, Christopher [OMP] wrote:
> Donald, thank you so much for your response. I had the opportunity to
> converse with my friend (HOH) on this matter again, and his explanation
> seemed to closely follow yours, or at least that's how I see it.
>
> I guess the bottom line
On Wed, 2 Aug 2000, chris (who, from his e-mail address, clearly does not
desire a personal response) wrote:
> I have a doubt as to what is the assumption for normality in a t-test.
>
> Two possibilities:
These may perhaps not exhaust the universe of discourse.
> I think it is for the sample
I have a doubt as to what is the assumption for normality
in a t-test.
Two possibilities:
I think it is for the sample data I have, while a dear
friend says it relates to the population and Central Limit
Theorem. I wrote:
"I went back to the reference on the t-test normality
assumptions and th
