Application of P/F Brass ratio method in the context of fast-paced adolescent fertility decline^*

Aplicación de la técnica P/F de Brass en un contexto de rápida caída de la fecundidad adolescente

Abstract

Adolescent fertility –fertility rates at ages 15-19– fell substantially (around 30 percent) between 2000 and 2010. It was the first time Brazil experienced such a decline in those ages since 1970, when the census included one question about children born in the past 12 months. This phenomenon has an important implication for the P/F Brass ratio technique: it underestimates the cumulated current fertility up to age group 20-24 (F₂), considering this cohort's previous fertility experience. Therefore, the P₂/F₂ value, used as an adjustment factor for the reported fertility level, is significantly overestimated. This paper discusses this issue and proposes an alternative to correct the reference period error in the 2010 Demographic Census in Brazil. The results of applying the proposed alternative in this specific context were very similar to those obtained using different techniques, thus supporting the strength of our alternative.

Key words
Brass P/F ratio; Fertility decline; Adolescent fertility; Census