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Modified Downs and Black scale for assessment of study quality
| 1 st Author (year) | Reporting (11) | External Validity (3) | Internal Validity bias (7) | Internal Validity Confounding (6) | Power (1) | Total quality score (28) |
|---|---|---|---|---|---|---|
| Hong-Wei Chen (2016)6 | 7 | 1 | 4 | 3 | 1 | 16 |
| Hong-Wei Chen (2017)7 | 7 | 1 | 4 | 3 | 1 | 16 |
| Chengwei Zhou (2018)8 | 8 | 1 | 3 | 3 | 1 | 16 |
| Tao i (2018)9 | 7 | 1 | 3 | 3 | 1 | 15 |
