Ricardo Ovaldia
> I used a log transform to normalize the distribution
> of a biochemical substance. I then use a ttest to
> compare the transformed mean of cases to controls. I
> now want to present my results listing the means, stds
> and the p-value. I could present the original
> (untransformed) means and stds, but I think that is
> misleading. Now, I know that the transformed mean is
> the geometric mean, so no problem there, but what
> about the standard error. How can I "untransform" it?
I am not at all clear that the se has an analogue
on the original scale.
I suggest that it is easier, and possibly
closer to the underlying problem, to exponentiate
the confidence intervals given by -ttest- for
the transformed means.
Another way to approach this is by
glm response caseorcontrol, link(log)
by analogy with the principle (e.g. Conroy Stata Journal
2002) that a t test is equivalent to a regression
on a binary explanatory variable.
Nick
[email protected]
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