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RE: <POSSIBLE SPAM>st: RE: RE: comparing different means using ttest


From   DE SOUZA Eric <eric.de_souza@coleurope.eu>
To   "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Subject   RE: <POSSIBLE SPAM>st: RE: RE: comparing different means using ttest
Date   Thu, 16 Dec 2010 19:26:58 +0100

Reply to original post, which once again I have deleted !

Why not just pool your data and regress %GDP-growth on a dummy (binary) variable (and a constant, of course) which takes the value of one for one of the two sub-samples and zero for the other; and test whether the coefficient on the dummy is significantly different from zero (or examine its confidence interval) ?
You can robustify for heteroscedasticity. 


Eric de Souza
College of Europe
Dyver 11
BE-8000 Brugge (Bruges)
Belgium

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: 16 December 2010 19:17
To: 'statalist@hsphsun2.harvard.edu'
Subject: <POSSIBLE SPAM>st: RE: RE: comparing different means using ttest

A senior Stata user, who might not want to be named, pointed out the counter-example of a Poisson variable. Clearly correct: if you know that your variable is Poisson, then the mean is also the variance. 

Nick
n.j.cox@durham.ac.uk 

Nick Cox

[...]
any more than the mean of anything tells you about its variability. 
[...] 


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