Also, they only compared those who scored very low to those that scored very high. The study says nothing about the predictive power of IQ for those who are wi

Also, they only compared those who scored very low to those that scored very high. The study says nothing about the predictive power of IQ for those who are within 'normal' ranges. All you can really conclude is that 13-year-olds with a WISC score above 130 tend to do better in life than kids with a WISC score below 85. It says nothing about if we can extrapolate that to conclude the kids scoring 115 do better than kids scoring 95.