Table 4.

Hypothetical Example 2. Statistical information fraction and critical values

Endpoint	Statistical information fraction at τl;, critical boundary function	Calendar time τl; (in months) at lth analysis
		24 (l =1)	36 (l =2)	48 (l =3)	60 (l =4)
PFS	${\mathcal{J}}_1\left({\tau }_l\right)/{\mathcal{J}}_1\left({\tau }_2\right)$	0.6511	1.0
	OBF	2.5444	1.9898
	POC	2.0798	2.2427
OS	${\mathcal{J}}_2\left({\tau }_l\right)/{\mathcal{J}}_1\left({\tau }_4\right)$	0.4157	0.7053	0.8866	1.0
	OBF	3.2860	2.4353	2.1703	2.0647
	POC	2.2122	2.3083	2.3708	2.4142

The significance level is α = 2.5%. The accrual duration is τ_A =24 months and the follow-up duration is ${\tau }_{f_1}=12$ months for PFS and ${\tau }_{f_2}=36$ months for OS. The HRs ψ₁ =0.65 for PFS and ψ₂ =0.70 for OS. The proportion of survivors after the follow-up duration is $S_1^{(1)}(36)=6.0\text{\%}$ for PFS and $S_2^{(1)}(60)=7.0\text{\%}$ for OS. Two analyses at 24 and 36 months for PFS and up to four analyses at 24, 36, 48 or 60 months for OS are planned.