karl pearson, the father of biometry, first used the term variance as follows:"it is here attempted to (show) the biometrical properties of a population of a more general type that has (..) been examined, inheritance in which follows this scheme. it is hoped that in this way it will be possible to make a more exact analysis of the causes of human variability. the great body of available statistics shows us that the deviations of a human measurement from its mean follow very closely the normal law of errors, and that therefore, the variablility may be uniformly measured by the standard deviation, corresponding to the square root of the mean square error."