Pierre-Simon, marquis de Laplace (23 March 1749 – 5 March 1827) was an influential French scholar whose work was important to the development of mathematics, statistics, physics and astronomy. He summarized and extended the work of his predecessors in his five-volume Mécanique Céleste (Celestial Mechanics) (1799–1825). This work translated the geometric study of classical mechanics to one based on calculus, opening up a broader range of problems. In statistics, the Bayesian interpretation of probability was developed mainly by Laplace.

Laplace is remembered as one of the greatest scientists of all time. Sometimes referred to as the French Newton or Newton of France, he has been described as possessing a phenomenal natural mathematical faculty superior to that of any of his contemporaries.

In 1812, Laplace issued his Théorie analytique des probabilités in which he laid down many fundamental results in statistics. The first half of this treatise was concerned with probability methods and problems, the second half with statistical methods and applications. Laplace's proofs are not always rigorous according to the standards of a later day, and his perspective slides back and forth between the Bayesian and non-Bayesian views with an ease that makes some of his investigations difficult to follow, but his conclusions remain basically sound even in those few situations where his analysis goes astray. In 1819, he published a popular account of his work on probability.[1]

The theory of probability, in essence, is nothing more than common sense, reduced to a calculation.

Pierre Laplace realized that certain error was inherent in all calculations. Instead of ignoring the error, he chose to quantify it, and the field of statistics was born. He even demonstrated that there was a mathematical distribution to the likelihood of error observed in given experiments. His student, Karl Peason, then took Laplace one step further and showed that not only there is a probability to the likelihood of error, but even our own measurements are probabilities. Pearson's revolutionary work laid the basis for modern statistics. After that, the early twentieth century geneticist Ronald Fisher introduced randomization and p-values, followed by A.Bradford-Hill, who applied there concepts to medical illnesses and founded clinical epidemiology.[2]

Laplace died in Paris in 1827. His brain was removed by his physician, François Magendie, and kept for many years, eventually being displayed in a roving anatomical museum in Britain. It was reportedly smaller than the average brain. Laplace was buried at Père Lachaise in Paris but in 1888 his remains were moved to Saint Julien de Mailloc in the canton of Orbec and reinterred on the family estate. [1]

- Pierre-Simon Laplace, in Wikipedia, accessed on 22 March 2017.
- A Clinician's Guide to Statistics and Epidemiology in Mental Health. By S. Nassir Ghaemi