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

Re: st: Producing incidence rates and weighted incidence rate


From   Michael Hills <mhills@blueyonder.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Producing incidence rates and weighted incidence rate
Date   Fri, 6 Jun 2003 11:59:54 +0000

I think your best bet might be to use poisson:

Create indicators for trainers using

. tabulate trainer, generate(X)

Use poisson to get rates by trainer

. poisson fract X* , e(time) nocons

where fract and time are my guesses at your variable names

Use testparm to test for differences in rates

. testparm X*, equal

Use poisson as above but without the X* to get an overall rate.


On Fri, Jun 06, 2003 at 11:47:43AM +0100, KRISTIEN VERHEYEN wrote:
> Dear all, 
> 
> I have dataset from a cohort study including horses, trainers, number of
> fractures and days at risk. Each observation consists of a horse with its ID
> number, the trainer by which it was trained, the number of fractures it
> sustained during the study period and the number of days it contributed to
> the study. 
> >From this, I would like to produce a table showing fracture incidence rates
> by trainer and also a weighted overall incidence rate, giving more weight to
> trainers who contributed more days at risk to the study. Also, is there a
> way Stata can tell me if the incidence rates between the trainers vary
> significantly (without having to produce IRR)?
> There are 13 trainers in the dataset, training 1178 horses, providing
> 386,803 days at risk. 
> 
> At this stage, I do not wish to stset my data, as there are some
> complications there with gaps and repeat events and I wouldn't think it 'd
> be that complicated to produce some simple IR and comparisons. I have used
> Stata help, searched FAQ and browsed the books but can not seem to find
> answers to these rather simple questions. Thanks very much for any help.    
> 
> Kristien Verheyen  
> 
> **********************************************
> Visit our website at www.aht.org.uk
> **********************************************
> 
> #####################################################################################
> This e-mail message has been scanned for Viruses and Content and cleared 
> by MailMarshal
> For more information please visit www.marshalsoftware.com
> #####################################################################################
> *
> *   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/

-- 
Michael 

mhills@blueyonder.co.uk


*
*   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