Twins may introduce a source of dependence in the ESCS data. Based on 20 000 resamplings of the 14 available unordered
pairs of twin data, the average correlation for the five ESCS dimensions were: IJA: r = .15, RJA: r = .004, IOR: r = .24, RR: r =−.10,RSI: r =−.08. As the between-pair variation is not significantly different from within-pair variation, this analysis indicated that it is reasonable to assume that ESCS data for twins are not dependent, and we therefore used analyses that assume independence.
Pearson correlations were computed between predictor variable (regulatory competence) and outcome ESCS elements,
and subsequently evaluated by t-tests. Multiple regression was used to test whether study group moderate the association
between temperament composite and social-communication elements