Figure 2.

SVM Classifiers Predict Individuals and Co-twin Pairs

(A) Mean SVM classifier accuracies, per group. Error bars are 95% confidence intervals. Both repeat visit subgroup accuracy scores were 1.0. Monozygotic (MZ) twins in both subgroups outperformed dizygotic (DZ) twins. Hatched box plots indicate when the opposite age group's feature mask was used for classification. All group accuracies are reduced when using the opposite mask, except for the Adult MZ twins. All groups' prediction scores were significantly better than chance, except the Adult DZ group when tested using the pediatric feature mask.

(B) Left: Distributions of accuracy scores in the twin groups, across age sets, show a similar distribution and mean accuracy score. Pediatric group distributions are outlined in black and the darker shade indicates overlap in age-grouped distributions. The spread of distributions reinforces the decision to shuffle twin labels to ensure that accidental group assignment bias does not influence group accuracy. Right: The pediatric same-sex sibling pair group outperformed pediatric DZ twins, suggesting an influence of sex on functional network organization.

(C) The area under the curve (AUC) values represent classifier sensitivity for each related scan pair. Repeat visit individuals are not plotted, as AUC values were 1.0 for all. A lower group average and larger distribution of AUC values in both DZ groups suggests that differences in DZ twin pairs' functional fingerprint resulted in more false-positives when classifying DZ twins than MZ twins. This is amplified in the adult DZ twins, compared with their pediatric counterparts.