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Table 4 Comparison of the mean absolute error for ln (HR) and var. ln (HR) using the Parmar, Guyot 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)

Validation

ln (HR)

Var ln (HR)

1. Nlopt method: exact P value

0.014 (0.007–0.022)

0.0039 (0.0022–0.0056)

13 KM plots (this study)

2. Nlopt method: non-exact P value

0.087 (−0.036–0.210)

0.0033 (0.0010–0.0055)

3. Parmar: this study

0.077 (0.039–0.115)

0.0038 (0.0016–0.0060)

4. Parmar

0.079 (0.048–0.110)

0.0104 (0.0070–0.0139)

48 KM plots [8]

5. Guyot: All information

0.017 (0.002–0.122)

0.0026 (2e-5–0.1332)

6 KM plots [16]

6. Guyot: No numbers at risk

0.036 (0.003–0.242)

0.0015 (6e-6–0.0541)

7. Guyot: No total events

0.028 (0.002–0.149)

0.0065 (2e-5–0.2497)

8. Guyot: No additional information

0.198 (0.021–1.556)

0.1227 (6e-4–3.2501)

  1. Ln (HR) and var. ln (HR) reported as mean absolute error with 95% confidence intervals. The var ln (HR) for Guyot were calculated from the published standard errors by using var. = SE^2*n