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Re: st: using expressions in margins command


From   Jordan Silberman <silberman.stata@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: using expressions in margins command
Date   Thu, 20 Jun 2013 10:44:50 -0400

Thanks for your response. It seems to take only integer powers--pos or
neg doesn't seem to matter. Even 1 decimal place yields the error
message. The exception is that, for some reason, fractional powers
between 0 and 1 seem to work.

On Thu, Jun 20, 2013 at 5:46 AM, Robert Duval <rduval@gmail.com> wrote:
> Hi Jordan,
>
> Did you try other non integer powers?
>
> What values does your predict(xb) take?
>
> Are they all strictly positive? Is any of them close to zero?
>
> I ask this question wondering whether there is a numeric precision
> problem given that you are dividing by your prediction, and you would
> get missing values if you divide by zero or something close to it.
>
> Robert
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