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Table 6 Extent of bias associated with misclassification* of the effectiveness algorithm according to observed response rate

From: Derivation and preliminary validation of an administrative claims-based algorithm for the effectiveness of medications for rheumatoid arthritis

Observed response rate True response rate** Bias (observed-true)/true (%)
30% 30% < 1%
40% 36% 10%
50% 43% 16%
60% 49% 21%
  1. *From Table 4, where the positive predictive value (PPV) was 76% and the negative predictive value (NPV) was 90%. **Computed as True rate = Observed rate × (PPV + NPV-1)-NPV + 1 [39]. Numbers are rounded to the nearest whole integer but the actual values were used to calculate the bias.