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st: Comparison of a distribution with a value from the literature


From   "Andrea Baccarelli" <andreastata5@hotmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Comparison of a distribution with a value from the literature
Date   Fri, 18 Apr 2003 17:42:50 +0000

I have the following question:

I am studying how the continuous variable A varies after a specific treatment.
In addition to compare A after the treatment with A before the treatment or in controls (no treatment), I need to compare it also with standard reference values from the literature.
Let's say that most book assume that A is equal to 1.0 with SD=0.2.

I thought to use the ttest command:

ttest A=1.0

I have two points:
1-This not take into account the variability (SD=0.2) of the measure taken from the literature. Does anyone have any suggestion about how to include it in the analysis?
2-Most variables in the study are not normally distributed. Is there any non-parametric test I can use to this end? [Stata's "ranksum" do not allow comparisons to a fixed value]

Thanks,
Andrea









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