c - usaid

2
"The age-specific model gives an estimate of overaLL
prevalence in the target year that is nott necessarily exactly the
same as the corresponding prevalence from the aggregate modal.
Tho reason for this generally minor discrepancy is that the agespecific
model takes into account variations in the age &tructure
of women of reproductive a ge. Since the aggregate modal ignores
these variations, the ago-specific version provides more accurate
estimates". /1
However, the input data needed for the age-specific veruion
raise two important questions:
i ] How wide may be the margin of error if an attempt is made to
express a fertility targat for a future year in term, of agespecific
ferti Lity rates which will necessarily involve subjective
Judgment?
ii I What can we say about the methodological impeccability of a
model which assumes that age-specific fertility rates can be
predicted with such accuracy ar to enable their use as an input?
This type of objection is particularly forceful in Bangladesh
because of uncertainty about the current ASFR's themselves, not to
speak of their predicted values.
In reply to the above questions, one could say that those who
are unhappy ubout the ag a-speci fic version should remain
content
with the aggregate modal. There is no doubt that the aggregate
model has been found to be very useful to those responsib l.e for
the family planning program in Bangladesh. But an exclusive use
of the aggregate model [if not supplemented by an age-specific
version] suffers from another type of shortcoming, namely that
the target is expressed here in terms of the total ferti lity
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/1 Bongaarts, J. and Sto,er, J. : The Population Counci l
Target-setting Model - A User's Manual. The Population council,
New York, 19B6, pp 12-14