TABLE 2.

Growth Curve Model results for Expressive Language AE. Both unstandardized and standardized coefficients are reported, where standardized coefficients can be used to compare the effect size between tests.

	Coefficient unstandardized/standardized		Std error	Z‐Score	p value	95% conf. interval
Intercept of expressive language
Delta	0.501	0.075	0.424	1.182	0.237	[−0.33, 1.331]
Theta	0.312	0.063	0.345	0.905	0.366	[−0.364, 0.988]
Low‐alpha	0.558	0.126	0.306	1.823	0.068	[−0.042,1.157]
High‐alpha	1.119	0.159	0.475	2.357	0.018	[0.189, 2.049]
Beta	0.745	0.121	0.413	1.805	0.071	[−0.064, 1.554]
Gamma	0.402	0.074	0.369	1.090	0.276	[−0.321, 1.124]
Group	−0.248	−0.096	0.165	−1.502	0.133	[−0.572, 0.076]
Site	0.249	0.096	0.197	1.268	0.205	[−0.136, 0.635]
biological sex	−0.066	−0.025	0.171	−0.385	0.701	[−0.4, 0.269]
6‐month nonverbal AE	0.426	0.626	0.051	8.279	<0.001	[0.324, 0.526]
Slope of expressive language development
Delta	−0.259	−0.042	0.526	−0.492	0.623	[−1.289, 0.772]
Theta	0.076	0.016	0.397	0.191	0.848	[−0.702, 0.854]
Low‐alpha	0.095	0.023	0.371	0.258	0.797	[−0.630, 0.821]
High‐alpha	0.280	0.042	0.588	0.477	0.633	[−0.871.1.432]
Beta	0.062	0.010	0.508	0.122	0.903	[−0.934, 1.058]
Gamma	−0.032	−0.001	0.438	−0.070	0.942	[−0.891, 0.827]
Group	−0.207	−0.087	0.203	−1.016	0.309	[−0.606, 0.192]
Biological sex	0.559	0.235	0.203	2.754	0.006	[0.161, 0.957]

Note: Biological sex was coded as (0 = Male, 1 = Female), group was coded as (0 = control infant, 1 = infant‐sibling).