(a) Percentage of antibodies and antigens yielding qualitatively correct results as a function of analyte concentration. An antibody or antigen was determined to yield qualitatively correct results if 100% of the replicate spots at or above a given concentration segregated above a low concentration threshold. The low concentration threshold was calculated by averaging the Cy5/Cy3 fluorescence ratio measured at the lowest tested concentration of the target antibody or antigen and adding two times the standard deviation of the ratio measured at the cognate spots. (T = X + 2S, where T = the threshold, X = the average, and S = the standard deviation.) (b) Percentage of antibodies or antigens yielding quantitatively correct results versus concentration. An antibody or antigen measurement was considered quantitatively accurate if it both fulfilled the criteria for qualitative accuracy in (a) and in addition, the measured R/G ratio fell within a factor of two of the known concentration ratio.