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| Random sequence generation |
| Criteria for judgment of “low risk” of bias | The articles that appropriately described the method of randomization |
| Criteria for judgment of “high risk” of bias | Articles that presented a methodological failure in the randomization criterion or the difficult reproducibility method |
| Criteria for judgment of “unclear risk” of bias | When the articles did not describe the method of randomization |
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| Allocation concealment |
| Criteria for judgment of “low risk” of bias | When the allocation sequences of samples were concealed in the randomization |
| Criteria for judgment of “high risk” of bias | When the sequences of allocation of samples were not concealed at randomization |
| Criteria for judgment of “unclear risk” of bias | When the allocation sequences were unreported |
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| Blinding of participants and researchers |
| Criteria for judgment of “low risk” of bias | When the sample was blind |
| Criteria for judgment of “high risk” of bias | If the methodology could not be blinded for whatever reason (sample/appraiser) |
| Criteria for judgment of “unclear risk” of bias | When the sample was not reported either way |
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| Blinding of outcome assessment |
| Criteria for judgment of “low risk” of bias | When the evaluators reported that the blinding in the evaluation was effective |
| Criteria for judgment of “high risk” of bias | If the study informed the evaluators how the blinding was done |
| Criteria for judgment of “unclear risk” of bias | When the blinding was not reported |
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| Incomplete outcome data |
| Criteria for judgment of “low risk” of bias | When there was an exhaustive description of the main data |
| Criteria for judgment of “high risk” of bias | If there was a loss due to an incomplete description of the main results regardless of quantity, nature, and manipulation |
| Criteria for judgment of “unclear risk” of bias | When the results were not reported |
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| Selective reporting |
| Criteria for judgment of “low risk” of bias | When the discussion excluded some of the results |
| Criteria for judgment of “high risk” of bias | When the article discussed the data completely |
| Criteria for judgment of “unclear risk” of bias | When the organization of the results in the discussion was unclear |
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