Figure 4From: The design and statistical power of treatment re-infection studies of the association between pre-erythrocytic immunity and infection with Plasmodium falciparumThe effect of sampling frequency (weeks between each evenly spaced sample assuming no seasonality in transmission) on statistical power and estimated hazard ratio. Statistical power at the 5% significance level to detect the effect of a pre-erythrocytic immune response that prevents 50% of infections in (A) a low transmission setting (EIR = 5), and (B) a high transmission setting (EIR = 150). Mean of estimated hazard ratios for infection associated with a ten-fold increase in antibody titre in (C) a low transmission setting (EIR = 5), and (D) a high transmission setting (EIR = 150).Back to article page