Statistics
Non/parametric analyses were used as appropriate and statistical tests used are indicated in the tables below. Alpha level was set at p < .01 to compensate for multiple comparisons although p < .05 variables are noted. Analysis of change in Wechsler IQ scores from early to later adulthood took account of the possible influence of the Flynn effect (increases in IQ scores from WAIS-R (Wechsler, 1981) to WAIS-III over time; Flynn, 2007; see Appendix S1[C]). As the results did not differ whether actual or adjusted scores were used, only actual scores are presented here. In the analysis of individual IQ change, data were also explored using the formula used by Remington et al. to determine ‘clinically significant change’.