Scatter plot of expression level variance between samples to define the highest signal to background ratio of calculated expression units for P. falciparum probes. Increasing concentrations of cRNA from the Nigerian sample were hybridized to the array and expression levels (Expression Units) for each transcript were derived using the MOID algorithm. 15 μg cRNA data is presented on the Y axis (a) 15 μg v. 30 μg of starting cRNA. (b) 15 μg v. 60 μg starting cRNA. (c) and 15 μg v. 120 μg starting cRNA. (R = correlation coefficient).