TABLE 2.
Parameter estimates from the linear multilevel analyses: age and verbal intelligence quotient (VIQ), and age and performance IQ (PIQ) for Autism Spectrum Disorder (ASD) and typically developing (TD) subgroups
| ASD | |||||||
|---|---|---|---|---|---|---|---|
| VIQ | |||||||
| Fixed effects coefficients (age) | Parameter Estimate | SE | 95% CIs | df | t value | p value | |
| β 0 intercept (grand‐average) | 66.20 | 0.92 | 64.39 | 68.01 | 5034 | 71.82 | <0.001 |
| β 1 slope (grand‐average) | ‐0.19 | 0.02 | −0.25 | ‐0.14 | 5034 | −7.05 | 1.9912e−12 |
| Random effects covariance (child) | Parameter Estimate | 95% CIs | |||||
| Intercept (SD) | 21.63 | 19.33 | 24.20 | ||||
| Age (SD) | 0.57 | 0.48 | 0.67 | ||||
| Correlation: age, intercept | ‐0.43 | ‐0.56 | ‐0.28 | ||||
| Observations | 5036 | ||||||
| R 2 | 0.75 | ||||||
| Adj. R 2 | 0.75 | ||||||
| F statistic | 49.74 (df = 1, 5034), p = 1.9912e−12 | ||||||
| Resid. SD | 15.73 (15.05 16.45 95% CIs) | ||||||
| PIQ | |||||||
| Fixed effects coefficients (age) | Parameter Estimate | SE | 95% CIs | df | t value | p value | |
| β 0 intercept (grand‐average) | 100.24 | 0.72 | 98.82 | 101.66 | 5034 | 138.81 | <0.001 |
| β 1 slope (grand‐average) | ‐0.69 | 0.02 | ‐0.74 | ‐0.65 | 5034 | ‐30.34 | 7.331e‐186 |
| Random effects covariance (child) | Parameter Estimate | 95% CIs | |||||
| Intercept (SD) | 17.66 | 16.04 | 19.45 | ||||
| Age (SD) | 0.56 | 0.50 | 0.62 | ||||
| Correlation: age, intercept | −0.62 | −0.69 | −0.54 | ||||
| Observations | 5036 | ||||||
| R 2 | 0.81 | ||||||
| Adj. R 2 | 0.81 | ||||||
| F statistic | 920.61 (df = 1, 5034), p = 7.331e−186 | ||||||
| Resid. SD | 12.05 (11.59 12.53 95% CIs) | ||||||
| TD | |||||||
|---|---|---|---|---|---|---|---|
| VIQ | |||||||
| Fixed effects coefficients (age) | Parameter Estimate | SE | 95% CIs | df | t value | p value | |
| β 0 intercept (grand‐average) | 95.77 | 1.13 | 93.55 | 97.99 | 1368 | 84.65 | <0.001 |
| β 1 slope (grand‐average) | 0.27 | 0.03 | 0.19 | 0.34 | 1368 | 6.96 | 4.9192e−12 |
| Random effects covariance (child) | Parameter Estimate | 95% CIs | |||||
| Intercept (SD) | 15.39 | 12.60 | 18.80 | ||||
| Age (SD) | 0.29 | 0.17 | 0.48 | ||||
| Correlation: age, intercept | −0.90 | −0.96 | −0.70 | ||||
| Observations | 1370 | ||||||
| R 2 | 0.31 | ||||||
| Adj. R 2 | 0.31 | ||||||
| F statistic | 48.57 (df = 1, 1368), p = 4.9192e−12 | ||||||
| Resid. SD | 13.34 (12.56 14.16 95% CIs) | ||||||
| PIQ | |||||||
| Fixed effects coefficients (age) | Parameter Estimate | SE | 95% CIs | df | t value | p value | |
| β 0 intercept (grand‐average) | 113.04 | 0.97 | 111.12 | 114.96 | 1368 | 115.52 | <0.001 |
| β 1 slope (grand‐average) | −0.16 | 0.03 | −0.23 | −0.09 | 1368 | −4.653 | 3.5882e−06 |
| Random effects covariance (child) | Parameter Estimate | 95% CIs | |||||
| Intercept (SD) | 10.45 | 7.86 | 13.89 | ||||
| Age (SD) | 0.20 | 0.06 | 0.59 | ||||
| Correlation: age, intercept | −0.74 | −0.90 | −0.43 | ||||
| Observations | 1370 | ||||||
| R 2 | 0.21 | ||||||
| Adj. R 2 | 0.21 | ||||||
| F statistic | 21.65 (df = 1, 1368), p = 3.5882e−06 | ||||||
| Resid. SD | 12.52 (11.78 13.31 95% CIs) | ||||||