From Hobson's Choice
Used in demographic analysis to represent population more precisely: one year lived by one person.
In the field of biostatistics, the person-year is used to estimate the probability of a particular event q, where the probability Pq is the number of incidents of q divided by the number of person-years observed ("followed"). When examining the growth in the incidence of certain age-sensitive cancers, for example, it is necessary to keep tabs on the number of person-years of a particular age cohort, since this number may fluctuate much faster and in a different direction from that of the general population. For example, the over-80 population in Germany is growing rapidly, while the overall population is in decline.
John Robert McNeill mentions the concept of the "human-year" as a benchmark of temporal population distribution; as, for example, approximately 20% of all human-years are believed to have been lived between 1900 and 2000.
- ↑ Bernard A. Rosner, Fundamentals of Biostatistics, Thomson Brooks/Cole (2006), p.119.
- ↑ John Robert McNeill, Something New Under the Sun: An Environmental History of the Twentieth Century, W. W. Norton & Company (2001), p.9ff (text online). McNeil cites Jean-Noel Biraben, "Essai sur l'evolution du nombre des hommes" Population (1979); Carl Haub "How Many People Have Ever Lived on Earth?" Population Today (Feb 1995); Jean Bourgeois-Pichat, Main Trends in Demography, Allen and Unwin (1973); and several others, but doesn't explain who supplies him with the numbers he actually used.
- John Robert McNeill, Something New Under the Sun: An Environmental History of the Twentieth Century, W. W. Norton & Company (2001),