5. Results of subgroup analyses.

Outcome	Subgroups		N°studies/ measures	N° participants	Mean effect size			Heterogeneity			Subgroup analyses
					SMD (95% CI)	Z	P	Chi2	P	I2 (%)	Chi2	DF	P	I2(%)
Mixed/regular word reading accuracy	Training type	Phonics only	3	232	0.94 (–0.09 to 1.97)	1.79	0.07	21.83	< 0.001	91	—	—	—	—
		Phonics + phoneme awareness	6	415	0.17 (–0.04 to 0.37)	1.61	0.11	4.35	0.50	0	—	—	—	—
		Phonics + sight word	2	54	0.73 (0.18 to 1.29)	2.58	0.01	0.61	0.43	0	5.22	2	0.07	61.70
	Training intensity	< 2 hours/week	9	577	0.54 (0.06 to 1.02)	2.19	0.03	50.68	< 0.001	84	—	—	—	—
		≥ 2 hours/week	2	124	0.34 (–0.02 to 0.70)	1.87	0.06	0.71	0.40	0	0.42	1	0.52	0
	Training duration	< 3 months	9	516	0.61 (0.17 to 1.05)	2.70	0.007	38.25	< 0.001	79	—	—	—	—
		≥ 3 months	2	185	0.12 (–0.43 to 0.67)	0.42	0.67	2.80	0.09	64	1.84	1	0.17	45.80
	Training group size	1	6	419	0.62 (–0.06 to 1.29)	1.78	0.07	44.35	< 0.001	89	—	—	—	—
		≤ 5	5	282	0.33 (0.04 to 0.61)	2.24	0.02	4.94	0.29	19	0.59	1	0.44	0
	Training administrator	Human	7	577	0.70 (0.17 to 1.23)	2.57	0.01	46.63	< 0.001	87	—	—	—	—
		Computer	4	124	0.18 (–0.20 to 0.51)	1.00	0.32	2.01	0.57	0	2.51	1	0.11	60.20
Non‐word reading accuracy	Training type	Phonics only	5	402	0.69 (–0.08 to 1.46)	1.75	0.08	48.66	< 0.001	92	—	—	—	—
		Phonics + phoneme awareness	5	280	0.63 (0.38 to 0.88)	4.86	< 0.001	1.84	0.77	0	0.02	1	0.89	0
	Training group size	1	7	454	0.83 (0.31 to 1.36)	3.10	0.002	37.34	< 0.001	84	—	—	—	—
		≤ 5	3	228	0.32 (–0.32 to 0.96)	0.97	0.33	9.64	0.008	79	1.47	1	0.23	31.80
	Training administrator	Human	4	388	1.12 (0.48 to 1.76)	3.42	< 0.001	22.23	< 0.001	87	—	—	—	—
		Computer	6	294	0.31 (–0.02 to 0.64)	1.85	0.06	8.81	0.12	43	4.84	1	0.03	79.40

CI: confidence interval; DF: degrees of freedom; SMD: standardised mean difference.