Table 3.

Mixed-effects Poisson regression models by SES/disadvantage indicator

	Model 1 IRR (95% CI)	Model 2 IRR (95% CI)	Model 3 IRR (95% CI)
Family has—or is at risk for—low income
Intercept	0.63 (0.53, 0.75)	0.68 (0.44, 1.05)	0.67 (0.43, 1.05)
Predictor	0.84 (0.80, 0.88)*
Centered predictor		0.84 (0.80, 0.88)*	0.84 (0.76, 0.94)*
Trial-level predictor		0.74 (0.35, 1.53)	0.75 (0.36, 1.55)
Random intercept variance	0.10 (0.04, 0.21)	0.10 (0.04, 0.21)	0.10 (0.05, 0.22)
Random slope variance			0.03 (0.01, 0.08)
Covariance: random intercept, random slope			0.01 (−0.02, 0.04)
Unemployed carer—there is no employed parent in the household
Intercept	0.59 (0.48, 0.72)	0.68 (0.47, 1.00)	0.68 (0.47, 1.00)
Predictor	0.88 (0.84, 0.93)*
Centered predictor		0.89 (0.84, 0.94)*	0.90 (0.82, 1.00)
Trial-level predictor		0.61 (0.27, 1.38)	0.62 (0.27, 1.41)
Random intercept variance	0.11 (0.05, 0.26)	0.10 (0.04, 0.24)	0.10 (0.04, 0.24)
Random slope variance			0.02 (0.00, 0.07)
Covariance: random intercept, random slope			0.01 (−0.03, 0.04)
Teenage parent—primary parent/s was younger than 20 at birth of target child
Intercept	0.59 (0.50, 0.69)	0.58 (0.44, 0.77)	0.58 (0.43, 0.77)
Predictor	0.90 (0.84, 0.96)*
Centered predictor		0.90 (0.84, 0.96)*	0.88 (0.77, 1.00)
Trial-level predictor		1.01 (0.20, 5.09)	0.99 (0.19, 5.20)
Random intercept variance	0.09 (0.04, 0.20)	0.09 (0.04, 0.20)	0.09 (0.04, 0.20)
Random slope variance			0.04 (0.01, 0.13)
Covariance: random intercept, random slope			0.00 (−0.04, 0.05)
Lone parent—the primary parent does not live with a partner or spouse
Intercept	0.59 (0.50, 0.70)	0.76 (0.49, 1.18)	0.79 (0.51, 1.22)
Predictor	0.92 (0.88, 0.97)*
Centered predictor		0.92 (0.88, 0.97)*	0.93 (0.86, 1.00)
Trial-level predictor		0.48 (0.16, 1.39)	0.43 (0.15, 1.26)
Random intercept variance	0.10 (0.04, 0.21)	0.09 (0.04, 0.19)	0.09 (0.04, 0.19)
Random slope variance			0.01 (0.00, 0.04)
Covariance: random intercept, random slope			0.01 (−0.01, 0.03)
Low education—highest educational level of primary
Intercept	0.63 (0.53, 0.75)	0.59 (0.40, 0.89)	0.58 (0.43, 0.80)
Predictor	0.81 (0.77, 0.85)*
Centered predictor		0.81 (0.77, 0.85)*	0.80 (0.70, 0.91)*
Trial-level predictor		0.94 (0.41, 2.14)	0.96 (0.54, 1.70)
Random intercept variance	0.10 (0.05, 0.22)	0.10 (0.05, 0.22)	0.10 (0.05, 0.23)
Random slope variance			0.05 (0.02, 0.13)
Covariance: random intercept, random slope			0.06 (0.00, 0.12)*

Model 1: IRRs for session attendance (uncentered)

Model 2: centered predictor model

Model 3: centered predictor model adjusting for baseline (intercept) values

^*Significant at the 0.05 significance level