TABLE 1.
Parameter estimates from the linear multilevel analyses: intelligence quotient (IQ) (Early Learning Composite [ELC] standard score) and age for Autism Spectrum Disorder (ASD) and typically developing (TD) subgroups
| ASD IQ (ELC) | |||||||
|---|---|---|---|---|---|---|---|
| Fixed effects coefficients (age) | Parameter Estimate | SE | 95% CIs | df | t value | p value | |
| β 0 intercept (grand‐average) | 82.74 | 0.79 | 81.18 | 84.30 | 2943 | 103.89 | <0.001 |
| β 1 slope (grand‐average) | −0.10 | 0.02 | −0.15 | −0.04 | 2943 | −3.53 | <0.001 |
| Random effects covariance (child) | Parameter Estimate | 95% CIs | |||||
| Intercept (SD) | 13.49 | 11.38 | 15.98 | ||||
| Age (SD) | 0.43 | 0.35 | 0.53 | ||||
| Correlation: age, intercept | −0.41 | −0.58 | −0.20 | ||||
| Observations | 2945 | ||||||
| R 2 | 0.66 | ||||||
| Adj. R 2 | 0.66 | ||||||
| F statistic | 12.843 (df = 1, 2943), p = 0.00034428 | ||||||
| Resid. SD | 11.53 (10.97 12.2 95% CIs) | ||||||
| TD IQ (ELC) | |||||||
|---|---|---|---|---|---|---|---|
| Fixed effects coefficients (age) | Parameter Estimate | SE | 95% CIs | df | t value | p value | |
| β 0 intercept (grand‐average) | 95.22 | 0.99 | 93.26 | 97.18 | 1179 | 95.25 | <0.001 |
| β 1 slope (grand‐average) | 0.40 | 0.04 | 0.31 | 0.49 | 1179 | 8.91 | 1.7447e−18 |
| Random effects covariance (child) | Parameter Estimate | 95% CIs | |||||
| Intercept (SD) | 7.71 | 4.73 | 12.57 | ||||
| Age (SD) | 0.31 | 0.20 | 0.49 | ||||
| Correlation: age, intercept | −0.20 | −0.70 | 0.43 | ||||
| Observations | 1181 | ||||||
| R 2 | 0.41 | ||||||
| Adj. R 2 | 0.41 | ||||||
| F statistic | 79.562 (df = 1, 1179), p = 1.7447e−18 | ||||||
| Resid. SD | 10.92 (10.19 11.71 95% CIs) | ||||||
Note: The ELC is the standard composite score on the Mullen, providing an estimate of IQ or g.