Thanks, Jeff, for your assistance. Just to clarify when using -svy
jackknife-, I assume Stata is estimating the parameters and SEs correctly on
the subpop, but it's just not reporting e(N_sub) correctly? Also, do you
know approximately when the update will be available?
Thanks,
Brent
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Jeff Pitblado,
StataCorp LP
Sent: Monday, February 12, 2007 9:28 AM
To: [email protected]
Subject: Re: st: reported subpop no. of observations seems wrong? and is
subpop needed with replicate wgts.?
Brent Fulton <[email protected]> has a few questions regarding the
-subpop()- option on -svy:
> With Stata 9, I am using survey regression with the subpop command
> e.g.,
>
> svy, subpop(var1): reg dep1 ind1
>
> The regression result reports "Number of obs" and "Subpop. no. of obs".
> Based on running a few scenarios, the "Number of obs" includes all
> observations that have non-missing values for the regression
> variables, including the weights. This is as expected; however, the
> "Subpop. no. of obs" seems to include all observations that have a "1"
> for the subpop, including those observations that have missing values
> for the regression variables.
>
> An actual example is below where I would have thought "Subpop. no. of obs"
> would have been 5329, not 5436. (This is a simple example. I am
> estimating several models with different sets of variables and am only
> able to find out how many observations Stata is really using by
> running an extra command such as: count if !missing(var1, var2,
> etc.).)
>
> Lastly, I know if I am using the Taylor series approach to estimate
> parameter standard errors within a subpopulation, subpop is required
> (i.e., this is wrong: svy: reg dep1 ind1 if female==1). However, if I
> am using replicate weights, is subpop required?
-svy jackknife- was failing to update the variable that identifies the
supopulation sample when the prefixed estimation command drops observations
due to missing values (or other reasons).
-svy linearized- and -svy brr- do not have this problem.
We should have -svy jackknife- fixed by the next ado-file update.
--Jeff
[email protected]
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