Stata The Stata listserver
[Date Prev][Date Next][Thread Prev][Thread Next][Date index][Thread index]

st: offset/exposure term in poisson analysis


From   "Anne Knol" <mailanne@post.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: offset/exposure term in poisson analysis
Date   Mon, 24 Jun 2002 16:54:08 -1100

Hello,

I'm trying to model the rate of a certain disease (amount of cases divided by population). Am I allowed to use an exposure/offset term for the population when modelling the rate?

Furthermore, when executing the poisson command I can use an exposure term but I can't use offset (while the help file claims that these options should give the same result). Stata comments: 

exposure = exp(pop) overflows;
could not estimate constant-only model
use exposure() option for exposure = pop

When I'm using the glm command (with family=poisson) in order to be able to allow for the overdispersion of my data, I'm not allowed to use an exposure term and when trying to use offset, I get the following error message: 

initial values not feasible r(1400)

Any ideas how to solve this problem so I can include include an exposure or offset term when using glm?

Thanks (and I know, I'm a stata beginner, so I'm sorry if these are stupid questions...)

Anne


Anne Knol 
Research Fellow 
Dept. Public Health 
Wellington School of Medicine, 
PO BOX 7343, Mein St 
Wellington, New Zealand 

-- 
__________________________________________________________
Sign-up for your own FREE Personalized E-mail at Mail.com
http://www.mail.com/?sr=signup

Save up to $160 by signing up for NetZero Platinum Internet service.
http://www.netzero.net/?refcd=N2P0602NEP8

*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/



© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   What's new   |   Site index