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

Table 5 Meta-regression results for the learning achievement of response from intervention duration

Model	Coefficient	Standard Error	95% lower	95% upper	Z-value	Two-sided p-value
Intercept	0.05	0.11	− 0.16	0.26	0.45	0.65	Q^b = 0.61, df = 5, p = 0.99
Intervention duration^a
1 = One week and less	0.12	0.20	− 0.28	0.51	0.58	0.56
2 = One month	0.14	0.43	− 0.70	0.99	0.33	0.74
3 = One trimester	0.02	0.28	− 0.52	0.57	0.08	0.94
4 = One year	0.15	0.38	− 0.59	0.89	0.40	0.69
5 = Not mentioned	− 0.05	0.29	− 0.62	0.52	− 0.17	0.86