The personal equation in ratings: II. A systematic evaluation

The personal equation "is defined as referring to spurious differences between the means of the standard deviations of two judges' ratings; the personal-equation effect is defined as the influence of spurious differences in means and standard deviations, upon the correlation of ratings with an adequate criterion." It is concluded that the latter has been greatly over-estimated and that improvements in technique can keep personal-equation effects at a very low figure.