Re: st: Predicted values where a subgroup of variables are held constant

[Tim Wade <wadetj@gmail.com>]

Is something like this what you are looking for?

sysuse auto.dta
regress price  mpg gear_ratio length weight
*price with covariates at means and mpg at 20
margins, at((mean) _all mpg=20)
*generate predicted results at means for each observation of mpg
adjust gear_ratio length weight, gen(yhat)
*confirm result is same for margins
list yhat if mpg==20


Tim


On Thu, Mar 17, 2011 at 5:11 PM, Michael Harhay
<michael.harhay@gmail.com> wrote:
> Dear all,
> I want to do a straightforward xb prediction after an OLS regression
> on a patient population, but for a subgroup of variables I want to use
> the sample mean not the true individual value for the prediction:
> I've been playing with both the "predict" and "margins" command but
> with no success. Is there an "if" like command I can put after predict
> to force this?
> After no success trying that I also tried to go about this in a roundabout way:
> preserve
> foreach var of local varlist `pred' {
>    sum `var’, meanonly
>    replace `var’ = r(mean)
>    }
>
> predict sev5, xb
> The predictions are still not adjusted.
> Any quick thoughts?
> Thanks!
>
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