Robert A LaBudde wrote:
At 01:40 PM 5/6/2010, Joris Meys wrote:
On Thu, May 6, 2010 at 6:09 PM, Greg Snow <greg.s...@imail.org> wrote:
Because if you use the sample standard deviation then it is a t test not a
z test.
I'm doubting that seriously...
You calculate normalized Z-values by substracting the sample mean and
dividing by the sample sd. So Thomas is correct. It becomes a Z-test since
you compare these normalized Z-values with the Z distribution, instead of
the (more appropriate) T-distribution. The T-distribution is essentially a
Z-distribution that is corrected for the finite sample size. In Asymptopia,
the Z and T distribution are identical.
And it is only in Utopia that any P-value less than 0.01 actually
corresponds to reality.
I'm not sure what you mean by this. P-values are simply statistics
calculated from the data; why wouldn't they be real if they are small?
Duncan Murdoch
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