Table 2.

β-coefficients of LMMs.

	Beta	SE	t-value	p-value
Phonemic skills (subscale vowels /syllables)
intercept	40.267	2.922	13.779	< .001
time t1	3.267	1.791	1.824	0.037
time t2	6.693	1.837	3.643	< .001
group	3.162	4.206	0.752	0.229
time t1 * group	-1.481	2.578	0.574	0.284
time t2 * group	-3.564	2.688	1.326	0.095
Phonemic skills (subscale words/sentences)
intercept	47.867	2.862	16.725	< .001
time t1	2.4	1.856	1.293	0.100
time t2	5.625	1.904	2.955	0.002
group	-4.581	4.119	-1.112	0.137
time t1 * group	4.529	2.672	1.695	0.048
time t2 * group	1.599	2.786	0.574	0.284
Spelling performance (alphabetic strategies)
intercept	39.533	2.763	14.307	< .001
time t1	-0.133	2.055	-0.065	0.474
time t2	0.133	2.107	0.063	0.475
group	-5.677	3.977	-1.427	0.080
time t1 * group	0.705	2.958	0.238	0.406
time t2 * group	2.960	3.082	0.960	0.170
Spelling performance (orthographic strategies)
intercept	36.8	2.146	17.151	< .001
time t1	2.333	1.261	1.849	0.035
time t2	2.621	1.294	2.025	0.024
group	-4.943	3.088	-1.601	0.059
time t1 * group	-0.691	1.816	-0.380	0.353
time t2 * group	3.503	1.894	1.850	0.035
Individual gamma frequency (power in µV*2)
intercept	8.891	2.047	4.342	< .001
time t1	-1.071	1.447	-0.741	0.231
time t2	1.651	1.447	1.141	0.13
Group	2.754	2.947	-0.934	0.177
time t1 * group	4.465	2.030	2.199	0.016
time t2 * group	2.180	2.095	1.041	0.152
Individual gamma frequency (peak frequency in Hz)
intercept	41.067	1.545	26.583	< .001
time t1	1.454	1.866	0.779	0.219
time t2	-1.438	1.866	-0771	0.222
Group	-0.781	2.223	-0.351	0.363
time t1 * group	1.591	2.621	0.607	0.273
time t2 * group	4.883	2.696	1.811	0.038