Table 2.
Parameter estimates (95% confidence intervals) and variances
| Model | |||||
|---|---|---|---|---|---|
|
| |||||
| Unconditional | Standard without covariates | Standard with covariates | Sibling-comparison without covariates | Sibling-comparison with covariates | |
|
| |||||
| b (CI) | b (CI) | b (CI) | b (CI) | b (CI) | |
| Intercept | 10.20b (9.86, 10.55) | 10.72 (10.24, 11.19)b | −.06 (−3.65, 3.53) | 10.67 (9.59, 11.74)b | 0.31 (−3.76, 4.39) |
| SDP | |||||
| SDP (CS) | −0.18 (−0.32, −0.03)c | −0.08 (−0.25, 0.08) | −0.17 (−0.32, −0.02)c | −0.02 (−0.22, 0.18) | |
| SDP (FA) | −0.18 (−0.51, 0.16) | −0.18 (−0.51, 0.15) | |||
| Controls | |||||
| Child | 0.50 (−0.19, 1.19) | −0.31 (−1.62, 1.01) | |||
| Mother education (CS) | −0.10 (−0.29, 0.10) | −0.03 (−0.48, 0.41) | |||
| Mother education (FA) | −0.11 (−0.33, 0.11) | ||||
| Mother age (CS) | −0.02 (−0.09, 0.05) | 0.31 (−0.07, 0.69) | |||
| Mother age (FA) | −0.02 (−0.09, 0.05) | ||||
| Mother marital status | −0.48 (−1.48, 0.52) | −0.44 (−1.47, 0.59) | |||
| Food stamps (CS) | −0.39 (−1.49, 0.71) | −1.36 (−3.34, 0.62) | |||
| Food stamps (FA) | 0.13 (−1.22, 1.48) | ||||
| Second-hand smoke exposure (CS) | 0.03 (−0.20, 0.26) | 0.05 (−0.37, 0.47) | |||
| Second-hand smoke exposure (FA) | 0.07 (−0.21, 0.34) | ||||
| IQ (CS) | 0.09 (0.06, 0.12)b | 0.09 (0.04, 0.14)b | |||
| IQ (FA) | 0.1 (0.07, 0.14)b | ||||
| Mother inhibitory control | 0.18 (0.05, 0.30)b | 0.19 (0.06, 0.32)b | |||
| Sex (CS) | 0.52 (−0.08, 1.13) | 0.79 (−0.03, 1.6) | |||
| Sex (FA) | 0.19 (−0.74, 1.13) | ||||
| Variance | |||||
| Family level | 1.74b | 0 | 0 | 1.77b | 1.03 |
| Individual-level | 6.58b | 5.93b | 5.66b | 6.56b | 5.20b |
| % Within-family variance explained beyond unconditional model | 9.88% | 13.98% | 0.3% | 20.97% | |
Note. SDP=smoking during pregnancy; b= unstandardized beta weights; CI=95% confidence interval; CS= child specific; FA= family average.
b
p<.01;
c
p<.05.