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Signals: two-by-two contingency table for a combination of positive and negative signals from medical forums and VigiBase to measure performance.
| Signals from medical forums | Signals from VigiBase | Total | |
| Positive | Negative | ||
| Positive | a (true positive) | b (false positive) | M1 |
| Negative | c (false negative) | d (true negative) | M2 |
| Total | N1 | N2 | N |
