c - usaid

44
At the moment, the obvious choicn for the base year is 1881,
since the latest population census wac conducted in that year
and
a contraceptive p rove' enc survey (CPS-81 ] was also conducted in
tho came year.
Forr purposes of ourr model, we naed ona more input,
namely, (iJ Age-specific naturel ferti lity pattern, expressed in
r Leative terms (Since this is an underlying patterrn,
it should be
applicable to the base year as wal as
to the tar-got years].
So far-, this aspect has not received much attention in
Bangladesh end no standard pattern of natural farti lity is
commonly accepted for this country. For developing countries in
general, a standard pattern was formulated by Coa e and Truase lL
(1974).
We have therefore experimented with many possible patterns
of natural farti lity, and finally chosen the following four:-
Pattern
I : Coale-Trussell pattern (without any modification);
Pattern II : Coo le-TrusselL pattern, modified for ages over 40;
Pattern III : Coo le-Trussel l pattern, modified fnr ages over 40
and be low 20;
Pattern
IV : Completely different from Coale-TrusseLl.
Since we have a
self-devised computer program, we can easily
experiment with additional patterns. We have found, however, that
the four patternc selected by us provide a fairIy wide choice, and
any new pattern is unlikely to make a significant impact on the
broad range of results that we have obtained by using Patterns I
to IV.