thank you for your answers,
evidently my question was not clear:
I am aware that STATA does not drop missing observations when using the
regress command, it just does not use them, but I expect the same regression
sample:
if I drop the missing observations before the regression as
if I just run the regression without dropping missing values...
thus, I don't understand why stata runs the regression on different samples
when I use the two commands described before
hope to have been clearer...
Mariarosaria
Citazione Maarten buis <[email protected]>:
> --- [email protected] wrote:
> > when I use the following command:
> > drop if x>450
> > STATA drops a lot of observations, while when I exclude missing
> > values as follows:
> > drop if x>450 & x!=.
> > STATA eliminates just a couple of observations
>
> This is well known behaviour: In Stata missing values are the largest
> possible values, so a missing value will be larger than 450. As result
> if you type -drop if x>450- the missing values will also be dropped.
>
> > I realized this when I run a regression including x as regressor. If
> > STATA drops missing data with the first command, shouldn't drop the
> > same observations when I run the regression after using the second
> > command?
>
> I don't think I understand the question. Do you think that -regress-
> should influence the way -drop- behaves?
>
> Maarten
>
> -----------------------------------------
> Maarten L. Buis
> Department of Social Research Methodology
> Vrije Universiteit Amsterdam
> Boelelaan 1081
> 1081 HV Amsterdam
> The Netherlands
>
> visiting address:
> Buitenveldertselaan 3 (Metropolitan), room Z434
>
> +31 20 5986715
>
> http://home.fsw.vu.nl/m.buis/
> -----------------------------------------
>
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