Pearson thought the best way to compare deviations in heights of men and women was to alter the deviations in the same ratio. The use of the standard deviation alone, which could be measured in centimetres or inches, would most likely show that men are taller on average, since they would have a higher mean value, but this wouldn’t answer the question: “Who shows more variation within their group?” Pearson devised the coefficient of variation to measure this. This was important to Pearson when he was trying to determine how variable some of Weldon’s prawns and crabs were.
