John Graunt (1620-1674)

John Graunt was a shopkeeper, a city councilman, an officer of a water company, and a member of the militia. He generally woke up early to study before opening his shop, which led him to ponder and study death and its causes. He examined the church records of London parishes, known as the Bills of Mortality. These records were likely recorded to monitor deaths due to the plague. Based on patterns he noticed in the records, he wrote Mathematical statistics: Natural and Political Observations Made upon the Bills of Mortality in 1662. From his observations, he noticed patterns and was able to guess at reasons for anomalies. Though he was one of the first to analyze data, his methods have remained a starting point for data analysis.

Graunt was the first Englishman known to calculate empirical probabilities (probabilities based on experimentation) and used his calculations to estimate the population of London in three different ways, arriving at similar conclusions each time. After seeing his work, Paris began publishing their own Bills of Mortality by 1670. His work showed the value of such records, which likely contributed to the appearance of birth, marriage, and death registrations for use by the government. These contributions to the early development of statistics, specifically initial analysis of collected data, led him to be known as the Father of Modern Statistics.