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| From | Maarten Buis <maartenlbuis@gmail.com> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | Re: st: Marginsplot after Poisson regression and negative predicted values |
| Date | Wed, 8 Jan 2014 15:11:36 +0100 |
What are the exact commands you used? The defaults should not result in negative predicted counts. -- Maarten On Wed, Jan 8, 2014 at 2:52 PM, James Bernard <jamesstatalist@gmail.com> wrote: > Forgot to add that I am not interested in confidence interval. My > dependent variable has maximum of 300. However, the maximum of y axis > on the predicted plot is 1 > > On Wed, Jan 8, 2014 at 9:47 PM, James Bernard <jamesstatalist@gmail.com> wrote: >> No, I mean that the Y variable that is a count variable on the y axis >> is negative, while my dependent variable is count variable >> >> On Wed, Jan 8, 2014 at 5:37 PM, Maarten Buis <maartenlbuis@gmail.com> wrote: >>> 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 <jamesstatalist@gmail.com> 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 >>>> * >>>> * For searches and help try: >>>> * http://www.stata.com/help.cgi?search >>>> * http://www.stata.com/support/faqs/resources/statalist-faq/ >>>> * http://www.ats.ucla.edu/stat/stata/ >>> >>> >>> >>> -- >>> --------------------------------- >>> Maarten L. Buis >>> WZB >>> Reichpietschufer 50 >>> 10785 Berlin >>> Germany >>> >>> http://www.maartenbuis.nl >>> --------------------------------- >>> * >>> * For searches and help try: >>> * http://www.stata.com/help.cgi?search >>> * http://www.stata.com/support/faqs/resources/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/faqs/resources/statalist-faq/ > * http://www.ats.ucla.edu/stat/stata/ -- --------------------------------- Maarten L. Buis WZB Reichpietschufer 50 10785 Berlin Germany http://www.maartenbuis.nl --------------------------------- * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/faqs/resources/statalist-faq/ * http://www.ats.ucla.edu/stat/stata/