Split a data set and run function
divide.conquer(func = NULL, data, size, splits, id = NULL, ...)
## avoid dependency on timereg
## library(timereg)
## data(TRACE)
## res <- divide.conquer(prop.odds,TRACE,
## formula=Event(time,status==9)~chf+vf+age,n.sim=0,size=200)