data(rott2)rott2 contains the following variables:
pre" and "post".<=20mm,>20-50mmm=20mm,> and >50mm.no" and "yes".no" and "yes".1978-87" and "1988-93".chemo" where "yes" is recoded as 0 and "no" is recoded as 1.chemo" is recoded into the numeric indicator variable "no.chemo": rott22$no.chemo <- as.numeric(rott2$chemo == "no") The follwing variables have been removed from the original dataset: enodes, pr_1, enodes_1, _st, _d, _t, _t0
since they are recodings of some existing variables which are not used in this analysis.