Comparison 2. Phonics training versus control: subgroup analyses (random‐effects model).

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Mixed/regular word reading accuracy	11		Std. Mean Difference (IV, Random, 95% CI)	Subtotals only
1.1 Training type: phonics alone	3	232	Std. Mean Difference (IV, Random, 95% CI)	0.94 [‐0.09, 1.97]
1.2 Training type: phonics + phoneme awareness	6	415	Std. Mean Difference (IV, Random, 95% CI)	0.17 [‐0.04, 0.37]
1.3 Training type: phonics + sight words	2	54	Std. Mean Difference (IV, Random, 95% CI)	0.73 [0.18, 1.29]
1.4 Training intensity: < 2 hours/week	9	577	Std. Mean Difference (IV, Random, 95% CI)	0.54 [0.06, 1.02]
1.5 Training intensity: ≥ 2 hours/week	2	124	Std. Mean Difference (IV, Random, 95% CI)	0.34 [‐0.02, 0.70]
1.6 Training duration: < 3 months	9	516	Std. Mean Difference (IV, Random, 95% CI)	0.61 [0.17, 1.05]
1.7 Training duration: ≥ 3 months	2	185	Std. Mean Difference (IV, Random, 95% CI)	0.12 [‐0.43, 0.67]
1.8 Training group size: 1‐on‐1	6	419	Std. Mean Difference (IV, Random, 95% CI)	0.62 [‐0.06, 1.29]
1.9 Training group size: small group (≤ 5)	5	282	Std. Mean Difference (IV, Random, 95% CI)	0.33 [0.04, 0.61]
1.10 Training administrator: human	7	577	Std. Mean Difference (IV, Random, 95% CI)	0.70 [0.17, 1.23]
1.11 Training administrator: computer	4	124	Std. Mean Difference (IV, Random, 95% CI)	0.18 [‐0.17, 0.54]
2 Non‐word reading accuracy	10		Std. Mean Difference (IV, Random, 95% CI)	Subtotals only
2.1 Training type: phonics alone	5	402	Std. Mean Difference (IV, Random, 95% CI)	0.69 [‐0.08, 1.46]
2.2 Training type: phonics + phoneme awareness	5	280	Std. Mean Difference (IV, Random, 95% CI)	0.63 [0.38, 0.88]
2.3 Training group size: 1‐on‐1	7	454	Std. Mean Difference (IV, Random, 95% CI)	0.83 [0.31, 1.36]
2.4 Training group size: small group (≤ 5)	3	228	Std. Mean Difference (IV, Random, 95% CI)	0.32 [‐0.32, 0.96]
2.5 Training administrator: human	4	388	Std. Mean Difference (IV, Random, 95% CI)	1.12 [0.48, 1.76]
2.6 Training administrator: computer	6	294	Std. Mean Difference (IV, Random, 95% CI)	0.31 [‐0.02, 0.64]