Grana et al. (2002) report results of a non-randomised clinical trial investigating a novel radioimmunotherapy in malignant glioma patients. The overall survival, i.e., the time from the beginning of the therapy to the disease-caused death of the patient, is compared for two groups of patients. A control group underwent the standard therapy and another group of patients was treated with radioimmunotherapy in addition. The data, extracted from Tables 1 and 2 in Grana et al. (2002), are given in Table 11.1. The main interest is to investigate whether the patients treated with the novel radioimmunotherapy have, on average, longer survival times than patients in the control group.