c - usaid

38
we hnve chosen a function of this typo.
For each target year, t h function PRF takes on seven
values, one for each five yearly age-group, starting from 15-19
and going up to 45-49. For K=0, all the values of PRF are equal
to one, ince exp(O) = 1. This means that K=0 represents a
s ituation wh r!re i,a reallocation of thu program is necas ary.
When K>O, tho value of PiF i t highest for those ago-groups
for which ASNFl (t) are tho highest, that i , for ago-groups 20-24
and 25-29.
The exprecsion within parentheses, namely
35 x AS NFR t] - TNFRC t) ...... (4.16)
is such that i ts average valuo for the seven ae-groups is zaro
because
5 ;27- A S NFR t TNFR(t)
An expression with an average zero value is necessary,
becaus o the rwise the u t] estimated thereby would not average
out to u[t). In fact, although the average vL'ue uf (4.16) is
zero, the average value of (4.15) is slightly more than on-a,
because of the characteristic properties of the exponential
function. Therefore, the u nadju J sted form (4.15] has to be
suitably "deflated"" to achieve the final form
1 35 ASNFR [t) - TNFR[ tI
PRFi (t) ...... .exp[K [----------------------] ....... (4.17]
14D1K 10
where D is a n "exponential average deflator " and K as wel L as D
can take values butwen 0 and 1.
Combining (4.131 and [4.i7],
the formula for estimating the agespecific
CPR' s for the target year i s