Grading of Strength of Findings of the Paper29
| Grade 1 | No clear conclusions can be drawn. Not significant. |
| Grade 2 | Results ambiguous, but there appears to be a trend. |
| Grade 3 | Conclusions can probably be based on the results. |
| Grade 4 | Results are clear and very likely to be true. |
| Grade 5 | Results are unequivocal. |