Wendy Johnson|Andrew D. Carothers|Ian J. Deary
Sex Differences in Variability in General Intelligence: A New Look at the Old Question
University of Edinburgh|Twin Cities Orthopedics|University of Minnesota|University of Edinburgh|University of Edinburgh
idea general intelligence may variable males females long history recent years presented reason little mean sex difference general intelligence yet males tend overrepresented top bottom ends overall presumably normal distribution clear analysis actual distribution general intelligence based large appropriately populationrepresentative samples rare however using two populationwide surveys general intelligence 11yearolds scotland showed substantial departures normality distribution less variability higher range lower despite mean iqscale scores 100 modal scores 105 even modal level males showed variability females consistent model population distribution general intelligence mixture two essentially normal distributions one reflecting normal variation general intelligence one refecting normal variation effects genetic environmental conditions involving mental retardation though present high end distribution sex differences variability appear account sex differences highlevel achievement