I think we need to see some precise evidence of
what you think is problematic. Thus, we need to
see _exactly_ what you typed and _exactly_ what
Stata did -- as the FAQ advises.
Nick
[email protected]
[email protected]
> 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
Maarten buis
> > --- [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?
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