On Mon, 11 Aug 2003 09:35:19 -0400, Ken Butler <[EMAIL PROTECTED]> wrote:
> On Mon, 11 Aug 2003 12:07:35 +0200, Piotr Wi�niewski <[EMAIL PROTECTED]> > wrote: > > >t-Student test > >log-transformed data > >------------------------ > > n mean SD > >X1 30 0.26 0.46 > >X2 6 -0.11 0.17 > > > >p=0.17 > > Are you using the "pooled" t-test that assumes equal population > variances for the two groups? > > If you are, this situation, where the smaller group also has the > smaller SD, can give very misleading P-values. That last comment is misleading, too. It implies that the *other* t-test is not (approximately) just as flawed. Which it is. I notice that the SDs are rather different for the log-transformed numbers, above, which does not lead one to regard the log fixing the matter. -- Rich Ulrich, [EMAIL PROTECTED] http://www.pitt.edu/~wpilib/index.html "Taxes are the price we pay for civilization." Justice Holmes. . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
