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Re: st: Test for trend for SIR


From   "raoul reulen" <r.c.reulen@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Test for trend for SIR
Date   Thu, 18 Oct 2007 12:40:38 +0100

Hi

I'm not exactly sure what you want to do, but the title of the message
suggests you want to do a test for linear trend accros several SIRs.
What I normally do is use smrby.ado because it includes a test for
trend and heterogeneity. Alternatively, you might want to model the
SIRs by using a GLM model with a Poisson error structure and then fit
the factor of interest as a consecutive non-negative integer variable.
Make sure you collapse your data before you model it.

.collapse (sum) _d E pyrs, by(timeperiod)
.xi, noomit:glm _d i.timeperiod if E!=0,fam(pois) lnoffset(E)  eform  noconstant

gives you the SIRs

.xi, noomit:glm _d timeperiod if E!=0,fam(pois) lnoffset(E)  eform  noconstant

gives you the p-value for linear trend

_d is the numner of events, E the number of expected. The p-value for
timeperiod should give you the test for linear trend accross the
groups.


Hope it helps

Raoul Reulen
Cancer Research UK Graduate Training Fellow





On 17/10/2007, roland andersson <rolandersson@gmail.com> wrote:
> I have used strate.ado to calculate standardised incidence ratios with
> standardisation for age, sex and timepriod. I want to make inferences
> on the development of the SIRs over three timeperiods. Can you help me
> with instruction how to do this?
> *
> *   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/
>


-- 
-------------------------------------------------------
Raoul C. Reulen
Cancer Research UK Training Fellow
*
*   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/



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