The quality rating of each study based on the Cochrane risk of bias assessment
Random sequence generation | Allocation concealment | Blinding (participants and personnel) | Blinding (outcome assessment) | Incomplete outcome data | Selective reporting | Other sources of bias | |
Angeles et al46 | Unclear | Unclear | High risk | Unclear | Low risk | Low risk | Low risk |
Baird et al45 | Unclear | Unclear | Unclear | Unclear | Low risk | Unclear | Low rIsk |
Fernald and Gunnar43 | High risk | High risk | Unclear | Unclear | Unclear | High risk | High risk |
Filmer and Schady52 | High risk | High risk | Unclear | Unclear | Low risk | Unclear | Low risk |
Kilburn et al40 | Unclear | Unclear | Low risk | Unclear | Low risk | Unclear | Low risk |
Kilburn et al51 | Unclear | Unclear | Unclear | Unclear | Unclear | Low risk | Unclear |
Macours et al50 | Low risk | Unclear | Unclear | Unclear | Unclear | Low risk | Low risk |
Özler et al48 | Unclear | Low risk | Unclear | Unclear | Low risk | Low risk | High risk |
Ozer et al42 | High risk | High risk | Unclear | Unclear | Low risk | Low risk | High risk |
Paxson and Schady49 | High risk | High risk | Unclear | Unclear | High risk | Unclear | High risk |
Shangani et al47 | High risk | High risk | Unclear | Unclear | Unclear | Low risk | High risk |
Tozan et al39 | Unclear | Unclear | Unclear | Unclear | Unclear | Low risk | High risk |