Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
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 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 <[email protected]> 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 <[email protected]> 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 <[email protected]> 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 <[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
>>>> *
>>>> * 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/