Table 1.
Descriptive statistics of key variables.
Fig 1.
Scatterplot of Social Capital (SCI) and Index of Relative Rurality (IRR).
Legend: SCI is plotted on the x-axis and IRR is plotted on the y-axis. Color saturation reflects greater representation. SCI is standardized to a t-score distribution (M = 50, SD = 10) and centered at 50 as shown; IRR is centered on 0.35.
Table 2.
Partial correlation and intraclass correlation coefficients (ICC).
Fig 2.
Parameter estimates of key variables on FSIQ, pre- and post-SES adjustment.
Legend: Mixed-effects parameter estimates reported account for clustering among siblings, sex, age, project, adopted status, race, ethnicity, and live together. Standardized estimates are plotted in red and blue for parameters unadjusted/adjusted [Unadj/Adj] for educational and occupational attainment, respectively. On the y-axis under each measure, we report the unstandardized estimates with standard errors. FSIQ = Full-Scale IQ; HPW = Log-transformed cognitive hours per week; Demand = Log-transformed average cognitive demand of reported hobbies; Number = Log-transformed number of cognitive hobbies; SCI = Social Capital Index; IRR = Index of Relative Rurality.
Table 3.
Parameter estimates and model fit for FSIQ.
Fig 3.
Full-Scale IQ (FSIQ) associations considering cognitive demand and interaction between Social Capital (SCI) and Index of Relative Rurality (IRR).
Legend: (A) FSIQ plotted by the interaction between SCI and IRR while controlling for cognitive demand. (B) FSIQ by cognitive demand varying on SCI and IRR. Figures plot over 95% of the sample, Urban = 0.24 IRR score, Rural = 0.46 IRR score, Higher SCI = 10 and Lower SCI = −10.
Table 4.
Sensitivity analysis: Parameter estimates and model fit for IQ, pre- and post-adolescent IQ adjustment.
Fig 4.
Full-scale and Performance IQ scores by Cognitive Engagement and Place, Pre- and post-adolescent IQ adjustment.
Legend: FSIQ = Full-scale IQ, PIQ = Performance IQ, SCI x IRR = Social capital (SCI) and rurality (IRR) interaction on IQ, Unadj/Adj = Unadjusted/Adjusted for adolescent IQ (IQ16). Panels A and C depict FSIQ and PIQ performance by cognitive engagement before (green) and after (blue) adjusting for IQ16. Panels B & D depict FSIQ and PIQ performance by social capital and rurality before (dashed) and after (solid) IQ16 adjustment. More rural (IRR = 0.46) is shown in red and more urban (IRR = 0.24) in blue. Inset panel forest plots show standardized estimates with 95% confidence intervals for cognitive engagement (Panels A & C) and SCI x IRR effects on FSIQ or PIQ (Panels B & D) before (green) and after (blue) adjusting for IQ16; see Table 4 for unstandardized estimates.