    # Re: st: Variance-Covariance matrix using -lincom-

 From "Stas Kolenikov" To statalist@hsphsun2.harvard.edu Subject Re: st: Variance-Covariance matrix using -lincom- Date Fri, 18 Aug 2006 13:54:53 -0500

```Besides -lincom-, you can use -nlcom- to compute non-linear functions
of the estimated parameters, and you will get the delta method
standard errors along with the point estimates. If you need your B3
it:

local B3 (1-1 - [b1]_cons - [b2]_cons)

so that then you can use something like

nlcom (alpha13: ln( [b1]_cons/`B3' ) ) (alpha23: ln ( [b2]_cons/`B3') )

On 8/18/06, JEFFREY ROSEN <rosen.53@osu.edu> wrote:
```
```Hello,

I've estimated a three equation LES model using an MLE. Due to constraints on
the system, only two equations are estimated and the third equation has  a linear
relationship with the other two.

B1 and B2 would be estimated and B3 = 1 - B1 - B2.

I've estimated B3 using the -lincom- command:

lincom 1 - [b1]_cons - [b2]_cons

I would like to calculate the standard error of some elasicities using the delta method. In order to do so, I need the variance-covariance matrix of all of the estimates. When I review the matrix using either -estat vce- or matrix list e(V), the matrix does not include the variable B3 that was estimated using -lincom-.

Is it possible to get the matrix to include B3?

Jeff Rosen
The Ohio State University

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```
```
--
Stas Kolenikov
http://stas.kolenikov.name
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```