Fig. 3
From: Sampling strategies to evaluate the prognostic value of a new biomarker on a time-to-event end-point
Power and design effect for different sensitivity levels (i.e. probability of having a positive surrogate if the biomarker is positive) of the surrogate variable. Scenario: specificity (i.e. probability of having a negative surrogate if the biomarker is negative) =0.7, censoring rate ρ = 0.1, hazard ratio of biomarker =1.5 and sample size of phase II (n) =600. Legend: CC stra surr (Case-Control stratified by surrogate), CC post surr (Case-Control post stratified by surrogate), CC event (Case-Control), CM (Counter-Matching) and SRS (simple random sampling)