Higher positive predictive values justify clinical trials with greater uncertainty or higher anticipated risk. The positive predictive value indicates the proportion of patients with a positive test (eg, biomarker values above a preset threshold) who have a diagnosis or outcome predicted by the test (eg, death within 1 year). A high probability of death, as indicated by a positive test, makes it ethically acceptable to test interventions that have uncertain outcomes or higher anticipated risk. Such uncertainty or risk would not be ethically acceptable in situations with a low probability of death.