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Lambert Adolphe Jacques Quetelet

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22 Feb 1796

Ghent, Flanders, Belgium

17 Feb 1874

Brussels, Belgium

Adolphe Quetelet received his first doctorate in 1819 from Ghent for a dissertation on the theory of conic sections . After receiving this doctorate he taught mathematics in Brussels, then, in 1823, he went to Paris to study astronomy at the Observatory there. He learnt astronomy from Arago and Bouvard and the theory of probability under Joseph Fourier and Pierre Laplace .

Influenced by Laplace and Fourier , Quetelet was the first to use the normal curve other than as an error law. His studies of the numerical consistency of crimes stimulated wide discussion of free will versus social determinism. For his government he collected and analysed statistics on crime, mortality etc. and devised improvements in census taking. His work produced great controversy among social scientists of the 19th century.

At an observatory in Brussels that he established in 1833 at the request of the Belgium government, he worked on statistical, geophysical, and meteorological data, studied meteor showers and established methods for the comparison and evaluation of the data.

In Sur l'homme et le developpement de ses facultés, essai d'une physique sociale (1835) Quetelet presented his conception of the average man as the central value about which measurements of a human trait are grouped according to the normal curve.

Quetelet organised the first international statistics conference in 1853.

The internationally used measue of obesity is the Quetelet index, sometimes also called the Body mass index (BMI).
This is:

QI = (weight in kilograms)/(height in metres)2

In non-metric measurements:
QI = (weight in pounds) 703/(height in inches)2

If QI > 30 then a person is officially obese.

Click here to calculate your Quetelet index

The portrait above is taken from a French stamp issued in his honour.

Source:School of Mathematics and Statistics University of St Andrews, Scotland