TEXT-BOOKS of statistics generally cite the coefficient of variation (or variability) as a measure of relative variability. While the coefficient (abbreviated to CV) is usually defined by the equation CV = 100/AM (which is the form to which these notes refer), the more general definition is of a specified measure of dispersion expressed as a percentage of some appropriate measure of central location. Simpson and Rowe1 give a list of seven formulae which by no means exhausts the logical possibilities.