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Table 2 Comparison of the mean absolute error and mean % absolute error using the Parmar method and nlopt method (exact and non-exact P value) described in this study

From: A non-linear optimisation method to extract summary statistics from Kaplan-Meier survival plots using the published P value

Method Mean Absolute Error (95% CIs) Mean % Absolute Error (95% CIs)
Ln (HR) Var ln (HR) Ln (HR) Var ln (HR)
1. Nlopt method: exact P value 0.014 (0.007–0.022) 0.0039 (0.0022–0.0056) 6.63% (2.69–10.57%) 20.12% (5.51–34.73%)
2. Nlopt method: non-exact P value 0.087 (−0.036–0.210) 0.0033 (0.0010–0.0055) 27.37% (8.69–46.05%) 17.30% (3.68–30.91%)
3. Parmar 0.077 (0.039–0.115) 0.0038 (0.0016–0.0060) 43.47% (11.18–75.77%) 20.06% (6.50–33.62%)
  1. The nlopt method using a exact and non-exact P value were compared with the Parmar method using a validation dataset of 13 KM plots. The mean absolute error and mean % absolute error for ln (HR) and var. ln (HR) were calculated for each method