Scatterplots and boxplots of pfmdr1 copy number estimate precision and Plasmodium falciparum beta-tubulin PCR cycle thresholds (Ct) for febrile clinical patients (grey circles and boxplots) and active screening participants (empty circles and boxplots) A: The scatterplots demonstrate precision of pfmdr1 copy number (CN) estimate (y-axis) diminishes as DNA concentration (x-axis) decreases among active screening participants (bottom panel) and febrile clinical patients (top panel). The mean cycle threshold and mean precision of pfmdr1 CN is indicated by the black point on each scatterplot. A three-cycle increase in the Ct corresponds to a 10-fold decrease in relative concentration of Pf DNA. Pfmdr1 precision is calculated as the range/mean for each isolate, with higher values indicating lower precision. The standard deviation of pfmdr1 CN estimates was 0.200 for clinic patients and .516 for screening participants (not shown) B: Boxplots display the distribution of DNA concentration (top panel) and pfmdr1 CN precision. Boxes represent inter-quartile ranges (IQR); whiskers represent the value of [upper/lower quartile +/− (IQR*1.5)]. Screening participants had lower DNA concentration and less precise estimation of pfmdr1 CN.