Farr, William

William Farr (1807–1883) had a major impact on the emergence of British social statistics, epidemiology, and demography in the mid-19th century and is considered to be a founder of medical statistics. Born in Shropshire, England, in 1807 to poor parents, Farr was effectively adopted by a local squire, Joseph Pryce, after his family moved to Dorrington. He was able to afford his medical education, receiving a licentiate from the Society of Apothecaries, through the inheritance from several benefactors. Farr married in 1833 and opened a medical practice in Fitzroy Square in London. His wife died in 1838 of tuberculosis, and he later remarried and had eight children.

During the 1820s and 1830s, Farr became interested in public health and medical statistics, and in the early 1840s, he played a key role in the development of a system of reporting the causes of death by medical personnel and the collection of these reports for local areas. Farr was also interested in comparative methods of classification of disease and causes of death; his work included comparisons of such methods in other European nations.

Farr served for many years as the Compiler of Abstracts of the Office of the Registrar General, a post that enabled him to serve as the major statistician of vital statistics for Great Britain. He was also a census commissioner for the 1861 and 1871 British censuses and served as president of the Statistical Society.

In 1849, there was a major outbreak of cholera in London that killed nearly 15,000 people. London, at the time, was one of the most populous cities in the world due to early industrialization, and as a result, the River Thames was heavily polluted with untreated sewage. While Farr was initially a proponent of the miasmic theory of disease, the theory that diseases were airborne, his detailed mapping of disease incidence in London, including data on social class and elevation, laid the groundwork for much 19th-century public health research. Although Farr was unconvinced by John Snow's efforts to show that cholera was of water-borne origin, he provided Snow with data on individual deaths from that disease, and his geographically based orientation toward disease incidence helped lay the groundwork for the acceptance of Snow's theory of water-borne transmission.

Farr's contributions to demography are less well-known to epidemiologists. By linking accurate vital statistics to the 1841 British census, he was able to show how cross-sectional measures like the census could be linked to dynamic measures of population processes derived from age-specific birth and death rates. Lewis credits him with originating the net reproduction ratio (NRR), a summary measure of the rate at which a population is reproducing itself net of the mortality rate. Farr's work in improving the accuracy of British population and vital statistics led succeeding generations of demographers to see these as a dynamic system. This led to the development of the linked equations of general population theory and the theory of stable populations (by Lotka and Dublin in the 1920s). [Page 396]The fact that their mathematical model of population dynamics could be easily demonstrated by population dynamics in late-19th-century Britain led to its widespread acceptance by demographers. These models also led to the influential computer simulations of population processes of Coale and Demeny (the families of model populations) and the development of quasi-stable population models. Farr's work in showing how accurate, age-specific cause-of-death statistics could be linked to census tabulations provided epidemiologists with the ability to measure risks of incidence and death in different population groups.

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