Statistical Analyses
Demographic and clinical factors were compared by radiation type (XRT vs PRT) using Chi Square, Fisher exact test, or independent t -tests, as appropriate. Group differences in social functioning and cognitive functioning were assessed using analysis of covariance (ANCOVA), covarying for the effects of time since radiation. Because peer relations and social skills did not differ by radiation type, remaining analyses examined the sample as a whole. To evaluate social outcomes among pediatric brain tumor survivors, one-sample t-tests compared peer relations and social skills with the normative mean of 50. Frequency data on the number of participants rated as having impaired social outcomes were examined, with impairment defined as scores falling 1.5 SD above the mean for peer relations (i.e. < standard score of 65) and 1.5 SD below the mean for social skills (i.e.> standard score of 35). Further, χ2 analyses determined whether the percentage of participants with impairment exceeded expectation assuming normal distribution of scores (6.68%). Bivariate correlations were run to examine relationships between social outcomes and demographic, clinical, and cognitive variables. Predictors were included in multiple linear regression analyses based on significant correlations with peer relations and social skills. Demographic and clinical variables that were significantly correlated (p < 0.05) with the specific outcome were included in the models. Cognitive skills that significantly correlated with either peer relations or social skills were also included (processing speed, executive functioning, verbal memory, and sustained attention).