Compare methods

	Parity Progression Ratio	Net Reproduction Rate
Field	Demography	Demography
Family	Process / pipeline	Process / pipeline
Year of origin	1953	2001
Originator	Louis Henry (formalized in modern demography)	Richard Böckh and Robert Kuczynski (formalized in Preston, Heuveline & Guillot)
Type	Order-specific fertility measure built from a sequence of conditional progression probabilities	Period measure of generational replacement combining fertility and mortality
Seminal source	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512	Preston, S. H., Heuveline, P., & Guillot, M. (2001). Demography: Measuring and Modeling Population Processes. Blackwell. ISBN: 9781557864512
Aliases	PPR, Birth progression ratio, Parity progression probability, Doğum Sırası İlerleme Oranı	NRR, Net reproduction ratio, Net reproductive rate, Net Üreme Hızı
Related	4	4
Summary	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.	The net reproduction rate (NRR) is the demographic measure of generational replacement: the average number of daughters a woman would bear who survive to the age their mother was when she bore them, given the period's age-specific fertility rates and female mortality. By combining fertility with survival, the NRR answers the fundamental question of whether a population is replacing itself — an NRR of one means each generation of women exactly reproduces the next, below one signals long-run decline, and above one signals growth.