Table 2.

Average Distance of Random Pairs of Genes on a Chromosome

Species	Average distance	SD
H. sapiens	62.79 Mb	14.1 Mb
C. elegans	5.58 Mb	0.89 Mb
D. melanogaster	7.76 Mb	1.39 Mb
A. thaliana	8.81 Mb	1.92 Mb
S. cerevisiae	0.33 Mb	0.077 Mb

This information may be used to determine if genes deviate enough from the random distribution to be considered clustered. We used the average distance minus three standard deviations as significance cutoff for defining genes to be included in loose clusters in Figure 3.