. Author manuscript; available in PMC: 2020 Nov 4.

Published in final edited form as: New Dir Child Adolesc Dev. 2019 Jul 1;2019(166):43–77. doi: 10.1002/cad.20305

Table 3.3.

Final Growth Curve Model Parameter Estimates for Mean Length of Utterances in Words (MLUw), Number of Different Words (NDW), and Words per Minute (WPM) in English

Parameter	UG-MLUw	CG-MLUw	UG-NDW	CG-NDW	UG-WPM	CG-WPM
Fixed Effects: γ (SE)
Intercept [γ₀₀]	7.9^b (0.03)	8.1^b (0.04)	100^b (0.7)	100.6^b (0.8)	93.4^b (0.7)	91.9^b (0.8)
Linear slope [γ₁₀]	0.21^b (0.009)	0.22^b (0.009)	3.9^b (0.1)	4^b (0.1)	0.83^b (0.1)	0.83^b (0.1)
Quadratic slope [γ₂₀]	0.01^b (0.0007)	0.01^b (0.0007)	0.2^b (0.01)	0.2^b (0.01)	−0.04^a (0.01)	−0.04^a (0.01)
Cubic slope [γ₃₀]	0.0003^b (0.00002)	0.0003^b (0.00002)	0.004^b (0.0003)	0.004^b (0.0003)	−0.001^b (0.0003)	−0.001^b (0.0003)
20% BRE_{@Grade 2} [γ₀₁]		−0.57^b (0.06)		−16.6^a (1.7)		−12.9^b (1.7)
English instruction (Ei) [γ₀₂]		−0.25^b (0.06)		5.4^b (1.3)		10.1^b (1.2)
Ei × linear slope [γ₁₂]		−0.02^b (0.003)		−0.26^b (0.05)
Variance Components: σ (SE)
Within-person variance [σ_ε²]	0.8^b (0.02)	0.79^b (0.02)	211.9^b (4)	209.2^b (4.9)	215.2^b (5)	214.8^b (5)
B/w-person intercept [σ₀²]	0.35^b (0.02)	0.33^b (0.02)	391^b (18.8)	341.2^b (16.7)	392.3^b (18.9)	344.1^b (16.8)
Proportional Variance Reduction
Within-person variance [R_ε²]	42%	42%	58%	59%	42%	42%
B/w-person intercept $R_{0}^{2}$		7%		13%		12%
Goodness-of-Fit
−2LL	14,060.2^b	13,951.3^b	42,763.3^b	42,573.4^b	42,827.5^b	42,683.4^b
BIC	14,111.2	14,027.8	42,814.3	42,650	42,878.5	42,751.4

Note. The proportional variance reduction of within-person variance [R_ε²] for the best fitting unconditional and conditional growth curve models was calculated based on the within-person variance of the unconditional means model (not shown) for each measure. UG = best fitting unconditional growth curve model; CG = best fitting conditional growth curve model; 20% BRE_{@Grade 2} = W-score performance at or below the 20th percentile at the end (spring semester) of Grade 2 in the broad reading cluster in English (BRE) of the Woodcock Language Proficiency Battery-Revised, W-score (Woodcock, 1991); −2LL = −2 log-likelihood deviance statistic; BIC = Schwarz’ Bayesian information criterion.

p < .01.

p < .001.