A list of years was taken and the network screened to the state in each of these years. First all nodes (i.e. species) that were not in the network at that point in the past were filtered out, also removing all edges attached to these nodes. All edges that were to be discovered only later were deleted and written to a separate list. Then a random selection of these edges was chosen as a test set (taken as true positives if showing up in the result set), called "chosen true edges" for the purposes of this chapter. Then ten times as many random edges which, to date, have not been discovered (taken as false positives if showing up in the result set) were added, called "chosen false edges". The likelihood ratios of all edges in that list were found.