Figure 1.

HRP-2 ELISA assay variability for the W2 Plasmodium falciparum parasite clone. Each data point represents an individual IC₅₀ value obtained from triplicate columns on each of three or five drug-coated plates, generating nine or 15 IC₅₀ values per experiment/occasion. For the drug stability experiment under field conditions, ODs from duplicate columns were averaged to generate a single IC₅₀ value for each plate, producing 26 IC₅₀ values for 26 assays run. All individual IC₅₀ values are presented in the “W2 Range” column. Red lines represent median IC₅₀s and interquartile ranges. ^(a) ‘Intra-assay’ variability is assessed by% CV of IC₅₀ values within each HRP-2 assay conducted by a single technician on a single day. ^{(b), (c)} IC₅₀ values measured from the same experiment were analysed in both the intra/inter-assay variability and long-term culture variability. ^(d) ‘Inter-assay’ variability was assessed by the % CV of IC₅₀ values among HRP-2 assays conducted on different days by the same technician, while technician performance was assessed by the difference in IC₅₀ values among technicians. ^(e) IC₅₀ values obtained from technician 1 were significantly lower than those from technician 2 and 3.