Figure 1. Causal diagram highlighting collider bias in Clarke et al. (2017) and Malaria Genomic Epidemiology Network et al. (2014).

G6PD deficiency is the exposure of interest (green) and cerebral malaria (CM) is the outcome of interest (red). By defining the CM cases as those who had coma but no severe anaemia, collider bias operates on the effect of G6PDd on CM.