Stover’s model

To overcome the limitations discussed in the previous page Limitations and Measurement Problems, Stover (1998) revised the Bongaarts model. The main changes of his revision are:

  1. Proportion of women who are sexually active is used instead of proportion married.
  2. Index of pathological sterility is added.
  3. Overlap between contraceptive use and infecundity is taken into account.
  4. Overlap between contraceptive use and postpartum amenorrhea is adjusted.
  5. Change from Total Fecundity to Potential Fertility as sterility is added.

 

Figure 12: Relationships between the fertility-inhibiting effects of the proximate determinants and various measures of fertility in Stover's revised model

Stover’s model

TFR = PF x Cx × Ci × Ca × Cu × Cf

where

  • TFR = total fertility rates
  • PF = potential fertility
  • Cx = index of proportion of women sexually active 
  • Cu = index of contraception
  • Ca = index of abortion
  • Ci = index of postpartum infecundability
  • Cf = index of infecundity

Because all the effects of infecundity have been accounted for in an infecundity index, the term Total Fecundity in the Bongaarts model is no longer appropriate to describe the residual fertility factor. Potential fertility is defined as the total fertility rate for a population of women who are sexually active and fecund for the entire period from age 15 to 49 and who do not practice breastfeeding, experience postpartum abstinence, nor practice contraception. Thus, this is higher than the previous concept of Total Fecundity and is an average value of 21.

The detailed calculations for each index can be found in Stover (1998).