This function estimates fbswicd object based on existing fbswicd object
and using the total population data.
esti_fbswicd(obj, pop = NULL)An estimated object with class of fbswicd.
The estimation proceeds in the following steps:
Calculate age-specific incidence and mortality rates for different sex and cancer sites.
Derive estimated counts of fbs and sws using the
rate × population formula.
Recalculate proportions (e.g., mv, dco) back to
estimated case counts.
Join all information and return a new object of the same class as obj.