ABSTRACT
Two groups of patients are treated with the anti-malarial drug A or B (Table 1). At the end of the study 8% (12/150) of the patients treated with drug A had contracted malaria and 12.3 % (43/350) patients treated with drug B had contracted malaria. The investigator wants to establish if the difference in infection rates is due to random variation alone or if there is a real difference between the two treatments.
