Figure 4.

A histogram of distances to the diagonal line from Fig. 2 (differences from repeated DNA microarray measurements). The curves are fit to log Gaussian, Eq. 4 (taller curve for the median of ratios), and log Lorentzian, Eq. 2 (wider curve for the ratio of medians), functions. Both curves were extracted from the same experimental data. There is an excess of points at 0 in the ratios of medians curve due to digitization of the measurements. The fit to the median of ratios curve is substantially under estimating the data at the transition from the base to the peak. The median of ratios has 3% of the points outside the range of −1 to 1, and 1.2% of the points outside the range of −1.2 to 1.2, whereas the ratio of median curve has 24% and 18% outside of the same ranges.