# Re: st: re: Could Stata give the variance of the parameter estimates?

 From krishanu karmakar To statalist@hsphsun2.harvard.edu Subject Re: st: re: Could Stata give the variance of the parameter estimates? Date Wed, 8 Jul 2009 18:31:01 -0400

```I think the "mean of x2" has to be saved in a scalar beforehand.
(however there may be other better ways)
for example
**************************
sum x2
scalar define meanx2=r(mean)
reg y x1 x2
di _b[x1]*meanx2
**************************
or if you do not want to use -scalar define- then
**************************
reg y x1 x2
sum x2
di _b[x1]*meanx2
**************************
Krishanu

On Tue, Jul 7, 2009 at 5:34 PM, <jjc.li@utoronto.ca> wrote:
> Thanks Kit! -nlcom- works in my case. I just know _b[x1] expresses the coef.
> of x1, but how to express the mean value of a variable? Like if I want to
> compute _b[x1]*"mean of x2"?
>
> Thank you so much!
>
> Crystal
>
> Quoting Christopher Baum <baum@bc.edu>:
>
>> <>
>> Crystal said
>>
>> There is another question. I am going to use these var and covar to
>> calculate the standard error for other factor (let's say SE(Mij)),
>> according to a given fomular. But how could I tell if the Mij is
>> significant at the 5% level, according to the calculated SE(Mij)?
>>
>> If you mean a linear combination of the coefficients, -help lincom-
>> If you mean a nonlinear " " ", -help nlcom-
>> Both will give you an S.E. and confidence interval for an expression
>> involving the coefficients' values.
>>
>> Kit Baum   |   Boston College Economics and DIW Berlin   |
>> http://ideas.repec.org/e/pba1.html
>> An Introduction to Stata Programming   |
>> http://www.stata-press.com/books/isp.html
>> An Introduction to Modern Econometrics Using Stata   |
>> http://www.stata-press.com/books/imeus.html
>>
>> *
>> *   For searches and help try:
>> *   http://www.stata.com/help.cgi?search
>> *   http://www.stata.com/support/statalist/faq
>> *   http://www.ats.ucla.edu/stat/stata/
>
>
>
>
> *
> *   For searches and help try:
> *   http://www.stata.com/help.cgi?search
> *   http://www.stata.com/support/statalist/faq
> *   http://www.ats.ucla.edu/stat/stata/
>

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