The modern era of statistics – the collection and analysis of numerical data in order to make statistical inferences – dates back to the mid-17th century. One of its key features is to take a representative sample of information and draw out from it broader assumptions about the whole data set.
Historically, statistics is closely aligned with demographics – the study of data related to society (such as births and deaths over a set time period) to discern trends within the population at large. The Roman Empire, for example, conducted censuses to gain a statistical overview of their dominions in terms of population, geographical extent, wealth etc. One of the earliest cases of non-demographic statistics was documented around the 5th century BCE by Thucydides, who described how the Athenians counted bricks in a section of the wall of Platea in order to calculate its full height. Having done so, they obtained ladders of the requisite length to scale the wall and launch an attack.
By the 9th century CE the Arab polymath Al-Kindi was describing how to use frequency analysis of statistics in order to break codes, and by the 16th century the concepts of the mean and median (respectively, the average value and the numerically middle value in a statistical set) were in widespread use. By the 18th century, figures such as Thomas Bayes and Pierre-Simon Laplace were bringing new rigour to the discipline, while William Playfair encouraged the graphical representation of statistical information in forms such as the line chart and bar chart.
Then, at the turn of the 19th century, Francis Galton and Karl Pearson ushered in a new wave of developments that saw statistics take on many of the characteristics it possesses today. Galton, for example, finessed concepts such as standard deviation – a value expressing by how much the members of a group differ from the group’s mean value. Pearson, meanwhile, strove to show how statistical analysis could be used to solve scientific problems. Furthermore, statistics now came to have greater social and political uses, whereas previously it had been a tool only for the mathematician and the scientist. For instance, Florence Nightingale heavily employed statistical analysis in her attempts to reform healthcare.
Big data
In the 21st century, the field of statistics continues to develop, not least in the arena of Big Data. Given the massive volumes of information collectable in our digital age (for instance, mobile phone records and receipts of sales transactions), statisticians are faced with the task of devising new ways to curate and process this data so as to be able to mine it for useful knowledge – in so doing, spawning an entirely new Big Data industry.