Are open educational resources (OER) and practices (OEP) effective in improving learning achievement? A meta-analysis and research synthesis

Table 4 Meta-regression results for the learning achievement of response from educational level

Model	Coefficient	Standard Error	95% lower	95% upper	Z-value	Two-sided p-value
Intercept	0.03	0.07	− 0.10	0.17	0.52	0.60	Q^b = 22.16, df = 3, p = 0.001**
Educational level^a
1 = Secondary	− 0.02	0.21	− 0.43	0.40	− 0.08	0.94
2 = Post-secondary	− 0.02	0.21	− 0.44	0.39	− 0.12	0.91
3 = Professional development	2.26	0.48	1.31	3.20	4.69	0.001**