Description
We calculate the variances of two classes of estimates of differential gene expression based on log ratios of fluorescence intensities from cDNA microarray experiments: direct estimates, using measurements from the same slide, and indirect estimates, using measurements from different slides. These variances are compared and numerical estimates are obtained from a small experiment involving 4 slides. Some qualitative and quantitative conclusions are drawn which have potential relevance to the design of cDNA microarray experiments.