Although he considered himself a haberdasher, John Graunt is better known as the founder of demography, the statistical study of human populations. With no formal training in mathematics, Graunt's work added immeasurably to human knowledge and his method of record keeping, an unknown technique more than three hundred years ago, contains lessons to be followed today. His work influenced another noted pioneer in this field, Sir William Petty, as well as Edmond Halley, English astronomer and "discoverer" of the comet named for him.
Born in London, England, on April 24, 1620, to Henry, a draper, and Mary Graunt, John was the eldest in a large family, and he eventually took over his father's business, as "haberdasher of small wares," a profession he continued for most of his life. His business and home, however, were destroyed in the London fire of 1666. A prosperous merchant, Graunt was a respected London citizen, holding various ward offices in the city and elected to the common council for two years. He was also a captain and later a major in a military band for several years.
While conducting his business, Graunt could not help but notice the mounting death toll in the city from the plague years, and he became curious about the offhand way records were kept by city officials covering deaths from the plague and other causes. This interest resulted in a short pamphlet to which Gaunt gave the long title of Natural and Political Observations mentioned in a following Index, and made upon the Bills of Mortality... With reference to the Government, Religion, Trade, Growth, Ayre, diseases, and the several Changes of the said City. This work, published in 1662 and generally called Observations, is given credit for beginning the idea that vital statistics, such as christenings and burials, could be used not only to keep records but to construct life tables for the entire population. Four editions of the pamphlet were eventually published, the third (1665) by the Royal Society, of which Graunt was a charter member.
Observations was Graunt's only scientific work, but it set a standard for record keeping that exists today. These are some of the lessons he left to modern-day epidemiologists: (1) be brief, (2) be clear, (3) test all theories before publishing them (for example, Graunt used five different ways to arrive at an estimation of the population of London), (4) invite criticism, (5) be willing to revise the data if necessary, and (6) do not be overly concerned with including data that is "only" statistically significant, which may result in important data being overlooked. In the 1620s, of course, Graunt had no interest in, nor knowledge of, "statistical significance testing."
In addition to his standards of record keeping, Graunt added to the store of human knowledge. He was the first to note the occurrence of more male than female births, but that because the male death rate was higher, the population count among the sexes was about equal. He refuted the theory that plagues are spread by contagion and showed statistically that, contrary to popular opinion, plague epidemics do not occur necessarily when a new monarch takes the throne. He was the first to estimate London's population and to show that the city's rapid growth was mainly the result of immigration. He offered first-time trends for many diseases. He classified death rates according to cause, including overpopulation, observing that death rates in the cities were higher than in rural areas. Perhaps Graunt's most important contribution was the introduction of his life tables. By using only two rates of survivorship--living to ages 6 and 76--he predicted the life expectancy of the population year by year and the percentage of persons who would live to each successive age. His colleague William Petty later was able to use these death rates in estimates of the economic losses that such deaths exact upon a community. Graunt is recognized today as having laid the foundations of the science of statistics. Graunt died in poverty on April 18, 1674.
This is the complete article, containing 665 words
(approx. 2 pages at 300 words per page).
