Validation of the DAPI ex vivo drug assay. A. Fluorescence intensity of maximum growth wells versus initial parasitaemia for parasites tested in the DAPI ex vivo drug assay. Pearson ρ = 0.47, linear slope P < 0.0001. B. Box plots showing signal-to-noise ratio (SNR) and Z’-factor for all assays. C-F. Bland-Altman plots showing differences between IC50 values of each technical replicate vs. average IC50 values for amodiaquine (C), artemisinin (D), chloroquine (E), and mefloquine (F). Horizontal lines indicate the mean difference in IC50 values between replicates. Intra-class correlation coefficients (ICC, with corresponding 95% confidence intervals) are displayed on each graph. G-I. Comparison of ex vivo with in vitro IC50 values for artemisinin (G), chloroquine (H), and mefloquine (I), among culture-adapted monoclonal parasites collected in 2009. Mean in vitro IC50 values are plotted with error bars showing the standard error of at least two biological replicates. ρ denotes the Pearson correlation coefficient.