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56
specifically, we establish Linkage between CPR, TFR and CBR. In
this way,
a direct an d clear answer is provided to the Bangladesh
population planners' question relating to CBR (referred to in
the
fi rst pare of this section) which Lay beyond the immediate scope
of the Population Counci l's rnodel.
Our model cons ist s of three
tags or blocks, namely,
I Bose year consistency searching block
II
III
Target year aggregate modelling block
Target y; aar age-spoci fic set-estimation block
The year 1921 is taken as the bose. year because th a
popuLation census as well as a contraceptive prevalence survey was
conducted in that year. In Block I, we have experimented with
different sets of values of ego-speci fic natural fertility rates
which, together with data on numbers of all woman, currently
varrid women, and rates of contraceptive prevalence in fiveyearly
age-groups, yield estimates of TFR and CBR for the base
year. By comparing these estimates of TFR and CBR with the
commonly accepted values of these rates for 1981, we can assess
whether the assumed pattrn1s of natural farti lity provide a­
reasonable fit to the Bangladshi situation, and if so, which of
those patterns can be expected to yield the most reliable
resu Lts.
After experiment ing with many patterns (with the help of
a self-designed computer program],
we have seLected the following
four sets of values of ago-specific natural fertility rates,
expressed in relative terms:­