Francis Galton : biography
This approach was later taken up enthusiastically by Karl Pearson and W.F.R. Weldon; together, they founded the highly influential journal Biometrika in 1901. (R.A. Fisher would later show how the biometrical approach could be reconciled with the Mendelian approach.) The statistical techniques that Galton invented (correlation, regression—see below) and phenomena he established (regression to the mean) formed the basis of the biometric approach and are now essential tools in all the social sciences.
Innovations in statistics and psychological theory
The method used in Hereditary Genius has been described as the first example of historiometry. To bolster these results, and to attempt to make a distinction between ‘nature’ and ‘nurture’ (he was the first to apply this phrase to the topic), he devised a questionnaire that he sent out to 190 Fellows of the Royal Society. He tabulated characteristics of their families, such as birth order and the occupation and race of their parents. He attempted to discover whether their interest in science was ‘innate’ or due to the encouragements of others. The studies were published as a book, English men of science: their nature and nurture, in 1874. In the end, it promoted the nature versus nurture question, though it did not settle it, and provided some fascinating data on the sociology of scientists of the time.
The Lexical Hypothesis
Sir Francis was the first scientist to recognize what is now known as the Lexical Hypothesis. This is the idea that the most salient and socially relevant personality differences in people’s lives will eventually become encoded into language. The hypothesis further suggests that by sampling language, it is possible to derive a comprehensive taxonomy of human personality traits.
Galton’s inquiries into the mind involved detailed recording of people’s subjective accounts of whether and how their minds dealt with phenomena such as mental imagery. In order to better elicit this information, he pioneered the use of the questionnaire. In one study, he asked his fellow members of the Royal Society of London to describe mental images that they experienced. In another, he collected in-depth surveys from eminent scientists for a work examining the effects of nature and nurture on the propensity toward scientific thinking.Clauser, Brian E. (2007). The Life and Labors of Francis Galton: A review of Four Recent Books About the Father of Behavioral Statistics. 32(4), p. 440-444.
Variance and standard deviation
Core to any statistical analysis is the concept that measurements vary: they have both a central tendency, or mean, and a spread around this central value, or variance. In the late 1860s, Galton conceived of a measure to quantify normal variation: the standard deviation.
Galton was a keen observer. In 1906, visiting a livestock fair, he stumbled upon an intriguing contest. An ox was on display, and the villagers were invited to guess the animal’s weight after it was slaughtered and dressed. Nearly 800 participated, but not one person hit the exact mark: 1,198 pounds. Galton stated that "the middlemost estimate expresses the vox populi, every other estimate being condemned as too low or too high by a majority of the voters",Galton, F., "", Nature, March 7, 1907, accessed 2012-07-25 and calculated this value (in modern terminology, the median) as 1,207 pounds. To his surprise, this was within 0.8% of the weight measured by the judges. Soon afterwards, he acknowledged"", Nature, March 28, 1907, accessed 2012-07-25 that the mean of the guesses, at 1,197 pounds, was even more accurate.
Experimental derivation of the normal distribution
Studying variation, Galton invented the quincunx, a pachinko-like device, also known as the bean machine, as a tool for demonstrating the law of error and the normal distribution .