Statistics

Censuses are used to enumerate a population and its characteristics. Statistics are mathematical calculations derived from this information or data that are collected and recorded in a numeric or quantitative format. Quantitative methods such as these have been used to describe human populations for hundreds, even thousands, of years. Censuses, or the numbering of people, occurred throughout the ancient world. For example, the Romans conducted censuses in order to determine household income for political (i.e., voting) and taxation purposes. The Han dynasty census from 2 ce China is the earliest, intact census surviving from ancient times; it shows that the population of this dynasty exceeded 57 million. Another notable census is the Doomsday Book , which was compiled in 1086 after the Norman invasion of England to determine the amount of wealth obtained from the conquest. Sometimes censuses are conducted on the dead as opposed to the living. In 1662, John Graunt reported the number of deaths in London over the preceding 30 years. He even analyzed mortality trends by gender, season, and location. Graunt eventually published the first “life tables,” used to compute life expectancy. In 1693, Edmund Halley refined Graunt's calculations to correctly compute life expectancy (Heyde & Seneta 2001). Censuses of human populations are still conducted throughout the modern world. The first census in the United States was taken in 1790, and censuses are done every 10 years in the US (US Census Bureau 2005).