Hi, I'm totally new to R so I apologise for the basic request. I am looking at the incidence of a disease over two time periods 1990-1995 and 2003-2008. I have counts for each year, subdivided into three disease categories and by males/females. I understand that I need to analyse the data using poisson regression and have managed to use the pois.daly function to get age-sex adjusted rates and corresponding confidence intervals. However, I now want to know how get a p value (I'm writing up a paper for a journal) to say that x number of cases in the first cohort (1990-1995) is significantly lower than y number in the later cohort (2003-2008). I also want to make sure that I've corrected for overdispersion etc. I'm totally stuck and can't think where to start with writing a script. So basically my question is: e.g. I have 271 cases of the disease between 1990-1995 (total population at risk over six years = 6,164,113) and 433 cases between 2003-2008 (total population at risk over sic year = 5,572,041) - is this significant and what is the P value. Any help much appreciated! Cheers P -- View this message in context: http://r.789695.n4.nabble.com/glm-poisson-function-tp2250210p2250210.html Sent from the R help mailing list archive at Nabble.com.
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