The standard deviation for the WISC is 15, so 1.75 standard deviations= 26.25. 150-26= 124. Or am I missing something?
Discrepancy in predicted achievement, properly done, is not based on a simple standard deviation difference. Firstly, both instruments have standard errors, so you have to take two sets of standard errors into account. Secondly, in linking studies (when available), it is not unusual to find more significant regression to the mean than would be expected simply by examining the range of overlap of the two confidence intervals. Such linking studies are available for the SBV/WJIII, WISC-IV (and -V)/WIAT-III, and WISC-IV (and -V)/KTEA-3. A true predicted achievement standardization set is available for the WJIII/WJIII. Correlational tables derived from unlinked standardization data are available for the WISC-IV/WJIII.
