Adolph Quetelet


Our society is named after Adolphe Quetelet, but who was Quetelet, and why did we choose his name? Let’s start with answering the latter question: Quetelet is considered as one of the fathers of statistics, and biometrics in particular. In the 19th century, long before the theories of Fisher and Pearson, Quetelet was among the first to use probability theory for analysing data. More about this later.

Adolphe Quetelet was born in Gent (Belgium) on February 22, 1796, during the French occupation. By the end of his secondary school, Belgium was under Dutch rule. In this period, the Dutch king Willem 1 established a new university, which is now known as Ghent University. Adolphe Quetelet was one of the first students. He was even the very first person to receive the diploma of Doctor of Philosophy in Natural Sciences and Mathematics. In those days, dissertations were written in Latin. Quetelet’s thesis, with the title “Dissertatio mathematica inauguralis de quibusdam locis geometris nee non de curva focali”, is still in the library of Ghent University.

After graduation, he started his career as a mathematics lecturer. However, his interests went much broader. He wrote poems and was interested in meteorology and astronomy. In 1823 he went to Paris to study meteorology and astronomy. During his visit, he also learned probability theory from Joseph Fourier and Pierre-Simon Laplace. He was considered very bright in astronomy (several publications), and he succeeded in persuading the Dutch government to establish an observatory in Brussels (this was later renamed to the Royal Observatory of Belgium). This happened in 1826, the year in which Quetelet turned 30 years of age. He also became the first director, which he remained until 1874). Thanks to his (inter)national recognition he was appointed as lecturer of mathematics and astronomy at the Royal Military School in 1836.

He also played an important role in meteorology. International collaboration has always been considered important by Quetelet. He was one of the driving forces to set up an international network to share observations, which was essential for the further development of both meteorology and astronomy.

Very relevant to our society, Adolphe Quetelet is internationally recognised as one of the fathers of statistical science. One of the reasons for this recognition is that he was one of the driving forces behind the first census to be held in Belgium (in 1848). Another is that he was one of the first to combine probability theory with data. He is assumed to be the first scientist to visualize data with a frequency diagram. A famous example is his analysis of the heights and chest circumferences of more than 5000 Scottish soldiers; the distributions approximated the normal distribution very well. Adolphe Quetelet saw Human as a central theme in his research. This brought him from astronomy to sociology; the latter being a discipline that was non-existing yet in those days. He understood that the complex relationships between variables that describe human behavior can be studied from data. For this purpose he needed mathematical methods, which he found in probability theory. He studied, for example, crime rates, and numbers of marriages and suicides. His most influential work was published in 1935. In that work he introduced the “average man” (l’homme moyen), who is characterised by the sample mean. He also gave his name to the Quetelet Index (or Body Mass Index, BMI). Because of his interest in measurements on humans and his essential role in the early days of statistics, he may also be considered as one of the fathers of Biometrics.

A few more trivia:

  • In 1841 Quetelet established the Central Commission for Statistics, which was worldwide the first national institute devoted to statistics.
  • In the early 19th century the Dutch the (later Belgian) Royal Academy for Literature and Fine Arts had a poor reputation as compared to, for example, the French academy. When Quetelet joined the academy, the academy quickly gained European fame. Quetelet became permanent secretary of the academy and stayed in this function for 40 years. As a tribute, a statue of Adolphe Quetelet can still be seen in front of the Royal Academy.
  • Quetelet composed a catalogue of about 100,000 stars. This is not left unnoticed by NASA, who named one of the moon craters after Quetelet.
  • Adolphe Quetelet also played an important role in the establishment of the Université Libre de Bruxelles (ULB, Free University of Brussels) in 1834.

Quetelet died in Brussels, on February 17, 1874.