Fig. 2.

Model validation. (A) Standard statistical model, Eq. 2. The maximum likelihood parameter estimate (red) fails to reproduce the distribution of observed feature intensities (black). (B) Physically grounded model, Eq. 9. The best fit (red) agrees extraordinarily well with the empirical data (A and B Insets). The physically grounded model strongly suggests that gene-expression levels decay according to a power law with an exponent of α ≈ 1.7.