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Re: st: Marginsplot after Poisson regression and negative predicted values
From
Maarten Buis <[email protected]>
To
[email protected]
Subject
Re: st: Marginsplot after Poisson regression and negative predicted values
Date
Wed, 8 Jan 2014 10:37:00 +0100
I suspect that you mean the confidence interval around the predicted
values. It is a known issue with the delta method that is used by
-margins- for computing the confidence interval. Generally I would not
worry too much about it, as these bounds are failry approximate
anyhow, but if you do you can predict the linear predictor with its
confidence intervals and transform those to the expected count metric
as in <http://www.stata.com/support/faqs/statistics/delta-rule/index.html>.
Hope this helps,
Maarten
On Wed, Jan 8, 2014 at 9:51 AM, James Bernard <[email protected]> wrote:
> Hi all,
>
> I have ran a Poisson model. Then tried to run -margins and
> -marginsplot for one of the variables.
>
> The shape of the graph makes sense. But, the range of predicted values
> of the dependent variable (which is a count variable, obviously)
> ranges from 1 at its maximum and -6 at its minimum. Is this usual? Am
> I doing something wrong?
>
> Thanks,
> James
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--
---------------------------------
Maarten L. Buis
WZB
Reichpietschufer 50
10785 Berlin
Germany
http://www.maartenbuis.nl
---------------------------------
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