Did you add in the constant?
. webuse grunfeld,clear
. qui areg invest kstock mvalue, ab(com)
. qui sum kstock
. local ks = r(mean)
. qui sum mvalu
. local mv = r(mean)
. qui sum invest
. local x1 = (_b[kstock]*`ks' + _b[mvalue]*`mv' + _b[_cons])/r(mean)
. disp "`x1'"
.999999999999999
Scott
> -----Original Message-----
> From: [email protected] [mailto:owner-
> [email protected]] On Behalf Of Terra Curtis
> Sent: Monday, March 06, 2006 1:35 PM
> To: [email protected]
> Subject: st: areg/xtreg
>
> I am using Stata 8.2. I have a question regarding what is written in
> the Stata manual for -areg-. The manual reports that "-areg- identifies
> the model by choosing the intercept that makes the prediction calculated
> at the means of the independent variables equal to the mean of the
> dependent variable: y(hat)=x(hat)*beta"
>
> I have used this fact to try to calculate the "percent of mean
> explained" by each independent variable in my regression. For
> concreteness, I have regressed like this:
>
> areg depvar indvar1 indvar2 indvar3, absorb(timevar)
>
> For the percent of mean explained calculation, I have taken each
> coefficient multiplied by the mean of that independent variable and
> divided by the mean of the dependent variable. After I have done this
> for all three independent variables, in theory the three percentages
> should add up to 1. However, this is not the case. Can anyone see why
> not?
>
> Thank you,
> Terra Curtis
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