How 'bout:
poisson model25
eststore mod25
poisson model30
eststore mod30
suest mod25 mod30
test [mod25_b*=mod30_b*]
or something similar...
Moleps
On Tue, Jan 20, 2009 at 6:43 PM, Lachenbruch, Peter
<[email protected]> wrote:
> Try writing your model for some specific values of age and exp
> You would have
> Ln(E(injury))=B0+B1*25+B2*exp+B3*25*exp+ln(hrs_day) for age 25
> Ln(E(injury))= B0+B1*30+B2*exp+B3*30*exp+ln(hrs_day) for age 30
>
> The difference is 5*B1+5*exp*B3
> Testing B3=0 is a test for same slope of regression line.
> The intercept is the same if B1 is 0 and B3 is 0. It may be helpful for
> interpretation to either center at the means, or find a 'smallest useful
> age' at center there. For example, use age 20 if that's a useful
> minimum age. Then the intercept B0 will refer to values at age 20.
>
> Tony
>
> Peter A. Lachenbruch
> Department of Public Health
> Oregon State University
> Corvallis, OR 97330
> Phone: 541-737-3832
> FAX: 541-737-4001
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of
> [email protected]
> Sent: Tuesday, January 20, 2009 3:12 AM
> To: [email protected]
> Subject: st: Testing for Significance Between Poisson Reg Lines
>
> I was wondering how I can go about testing for a statistically
> significant difference between the two lines produced below?
> age=age of person
> exp=amount of time doing a certain job
> hrs_day=number of hours worked on a given day
> injury=whether or not the person was injured (0/1)
> hrs_day and injury are summed by age and exp. age and exp are integers.
>
> poisson injury age exp ae if hrs_day>0, exposure(hrs_day)
> replace age= 25
> replace ae= 25*exp
> predict y_age25, ir
>
> replace age = 30
> replace ae = 30*exp
> predict y_age30, ir
>
> twoway (line y_age25 exp)(line y_age30 exp)
>
> Thanks.
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/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/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/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
