Table 2.
Comparison of relative risk estimates for the occurrence of severe hypoglycemia (BG < 40mg/dL) at three time points
| Interim Analysis |
Estimated Probabilities | Estimated Relative Risk |
|||
|---|---|---|---|---|---|
| Estimator | Group 1 | Group 2 | 95% CI | ||
| 1 | Observed data (Successes/Trials) | 0/3 | 0/4 | ||
|
| |||||
| Wald | 0.0000 | 0.0000 | Undefined | N/A | |
| Add psi=0.5 | 0.1250 | 0.1000 | 1.25 | [0.03, 50.2] | |
| Add psi=1.0 | 0.2000 | 0.1667 | 1.20 | [0.1, 14.69] | |
| Agresti-Min Uncond. Exact | - | - | - | - | |
| Approx. Uncond. Exact | - | - | - | - | |
| MUE-based | 0.1032 | 0.0796 | 1.30 | [0.21, 8.06] | |
|
| |||||
| 2 | Observed data (Successes/Trials) | 1/9 | 0/11 | ||
|
| |||||
| Wald | 0.1111 | 0.0000 | ∞ | [0,∞) | |
| Add psi=0.5 | 0.1500 | 0.0417 | 3.6 | [0.16, 79.01] | |
| Add psi=1.0 | 0.1818 | 0.0769 | 2.36 | [0.25, 22.7] | |
| Agresti-Min Uncond. Exact | 0.1111 | 0.0000 | ∞ | [0.173, ∞) | |
| Approx. Uncond. Exact | 0.1111 | 0.0000 | ∞ | [0.325, ∞) | |
| MUE-based | 0.1269 | 0.0305 | 4.16 | [0.35, 13.89] | |
|
| |||||
| 3 | Observed data (Successes/Trials) | 1/12 | 1/15 | ||
|
| |||||
| Wald | 0.0833 | 0.0667 | 1.25 | [0.09, 17.98] | |
| Add psi=0.5 | 0.0833 | 0.0667 | 1.25 | [0.09, 17.98] | |
| Add psi=1.0 | 0.1429 | 0.1177 | 1.21 | [0.2, 7.55] | |
| Agresti-Min Uncond. Exact | 0.0833 | 0.0667 | 1.25 | [0.08, 20.38] | |
| Approx. Uncond. Exact | 0.0833 | 0.0667 | 1.25 | [0.13, 11.57] | |
| MUE-based | 0.0961 | 0.0773 | 1.24 | [0.13, 11.46] | |
Both the Agresti-Min unconditional exact and the asymptotic unconditional method were computed in StatXact v6.2 using the two-sided test inversion method. StatXact was unable to compute the unconditional exact confidence intervals for Interim Analysis 1 on account of the 2×1 table structure.