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Re: st: Predicting number of cases


From   Christiana Titaley <christiana.titaley@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Predicting number of cases
Date   Sun, 5 Dec 2010 16:31:37 +1100

Hi Austin,

Thank you for your response. What I want to do is to examine the
trends of neonatal deaths across 5 surveys; whether the changes in the
predictors included in the Poisson model contributed to the reduction
of neonatal deaths over time.

E.g, using the grunfeld dataset,

u if time==1 using http://www.stata-press.com/data/r11/grunfeld.dta, clear
poisson invest mvalue kstock, r
predict hat

This will give me the predicted number of hat for time 1 and also the
predicted equation. I want to apply this equation (time 1) to the
subsequent data (time 2, 3 ...) to get the predicted number of "hat"
by controlling for the same set of predictors (mvalue, kstock). At the
end, I will compare the observed and predicted numbers of hat.

Please correct me if I'm wrong, but my understanding from the command
below is it uses the equation from time 2, instead of time 1, to get the
number of hat for year 2:
u if time==2 using http://www.stata-press.com/data/r11/grunfeld.dta, clear
predict hat
li hat mvalue, clean

Do you have any idea what command I can use to apply the first
equation (time 1) to the subsequent survey data?

Thank you very much.

Christiana


On Fri, Dec 3, 2010 at 12:00 AM, Austin Nichols <austinnichols@gmail.com> wrote:
> Christiana Titaley <christiana.titaley@gmail.com> :
> Use -predict- e.g.
>
> u if time==1 using http://www.stata-press.com/data/r11/grunfeld.dta, clear
> poisson invest mvalue kstock, r
> predict hat
> li hat mvalue, clean
> u if time==2 using http://www.stata-press.com/data/r11/grunfeld.dta, clear
> predict hat
> li hat mvalue, clean
>
> But can you explain the rationale for what you are doing?
>
>
> On Thu, Dec 2, 2010 at 5:15 AM, Christiana Titaley
> <christiana.titaley@gmail.com> wrote:
>> Hi all,
>>
>> I have data from 5 subsequent health surveys. Using data from the
>> first survey, I constructed a Poisson model using a set of potential
>> predictors to examine factors associated with neonatal death. The
>> final model gave me a predictive equation. Then I’d like to apply this
>> predictive equation to the data from subsequent years to determine the
>> predicted number of neonatal death cases. What command should I use
>> for this?
>>
>> Thank you very much.
>>
>> Christiana
>> University of Sydney
>
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