*** POISSON AND NEGATIVE BINOMIAL REGRESSION

* Read in the data from {SARS.xls} ;


PROC IMPORT DATAFILE = 'C:\Documents and Settings\richc\My Documents\CPH931F09\SARS.xls'
     OUT = GenLinMod   DBMS = EXCEL REPLACE;
     SHEET = SARS;
     GETNAMES = YES;
RUN;



* Initiate a ``transcript'' in the Word file {SARSresults.rtf}. ;


ODS RTF FILE = 'C:\Documents and Settings\richc\My Documents\CPH931F09\SARSresults.rtf';



* Fit a Poisson regression model, using only the data from Hong Kong,
* in which the number of new infections on a given day is related to
* how much time has passed since the epidemic has been monitored, 
* the mean temperature on that day, and the mean humidity on that
* day.  Note that TIME2 is a quadratic term. ;


PROC GENMOD DATA=GenLinMod;
WHERE COUNTRY='HK';
MODEL DAILYINF = TIME TIME2 MEANTEMP MEANHUM / LINK=LOG DIST=POISSON;
RUN;



* Refit the Poisson regression model with an adjustment for overdispersion. ;


PROC GENMOD DATA=GenLinMod;
WHERE COUNTRY='HK';
MODEL DAILYINF = TIME TIME2 MEANTEMP MEANHUM / LINK=LOG DIST=POISSON  SCALE=DEVIANCE ;
RUN;



* Fit a negative binomial regression model. ;


PROC GENMOD DATA=GenLinMod;
WHERE COUNTRY='HK';
MODEL DAILYINF = TIME TIME2 MEANTEMP MEANHUM / LINK=LOG DIST=NEGBIN;
RUN;


* End Word transcript. ;

ODS RTF CLOSE;
RUN;