השוואת שיטות

	Brass P/F Ratio Method	Parity Progression Ratio
תחום	דמוגרפיה	דמוגרפיה
משפחה	Process / pipeline	Process / pipeline
שנת המקור	1964	1953
הוגה השיטה	William Brass	Louis Henry (formalized in modern demography)
סוג	Indirect fertility estimation adjusting period rates using reported parities	Order-specific fertility measure built from a sequence of conditional progression probabilities
מקור מכונן	Brass, W. (1975). Methods for Estimating Fertility and Mortality from Limited and Defective Data. Carolina Population Center, University of North Carolina at Chapel Hill.	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512
כינויים	P/F Ratio Method, Brass P/F Ratio Technique, Parity/Fertility Ratio Method	PPR, Birth progression ratio, Parity progression probability, Doğum Sırası İlerleme Oranı
קשורות	4	4
תקציר	The Brass P/F ratio method is the foundational technique of indirect fertility estimation, designed to correct fertility levels in populations whose vital registration is incomplete but where a census or survey reports both recent births and lifetime children ever born. It compares F — the period fertility a synthetic cohort would have accumulated by each age — with P, the average parity (children ever born) actually reported by women of that age. The ratio of the two diagnoses and corrects errors in the reported level of current fertility, yielding an adjusted total fertility rate from data too defective for direct calculation.	A parity progression ratio is the conditional probability that a woman who has already had a given number of children goes on to have one more. By converting a static parity distribution into a sequence of birth-by-birth transition probabilities, the method reveals where childbearing stops within a cohort and lets demographers rebuild completed fertility from the bottom up. It is the natural fertility analogue of a survival or life-table transition, treating each additional birth as a further step a woman may or may not take.