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

 From Steven Samuels To statalist@hsphsun2.harvard.edu Subject Re: st: RE: RE: comparing different means using ttest Date Thu, 16 Dec 2010 15:17:16 -0500

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```
But. Eric, I don't think that pooling will solve the dependence issues that Nick mentioned.
```

Steve

sjsamuels@gmail.com

On Dec 16, 2010, at 1:26 PM, DE SOUZA Eric wrote:

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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