The ratio of essential genes(solid boxes) and the P-values(dashed line) for the number of essential genes observed in S. cerevisiae TRN in each level of the hierarchy. The network is divided into five different levels using the reachability penalty. The P-values are calculated based on the hypergeometric distribution.
Gülsoy et al. BMC Bioinformatics 2012 13:250 doi:10.1186/1471-2105-13-250