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Table 3 Parameters for directed networks

From: Testing biological network motif significance with exponential random graph models

Effect Description
Arc Baseline density
Sink A positive parameter value indicates a tendency for nodes with incoming but no outgoing arcs
Source A positive parameter value indicates a tendency for nodes with outgoing but no incoming arcs
Reciprocity A positive parameter value indicates a tendency for arcs to be reciprocated (a cycle of length 2)
AltInStars Alternating k-in-stars. A positive parameter value indicates centralization based on high in-degree nodes
AltOutStars Alternating k-out-stars. A positive parameter value indicates centralization based on high out-degree nodes
AltTwoPathsT Multiple 2-paths. A positive parameter value indicates a tendency for directed paths of length 2. Used as a “control” for AltKTrianglesT, the parameter for triangles formed by closing these 2-paths
AltKTrianglesT Path closure or transitive closure. A positive parameter value indicates a tendency for open directed two-paths to be closed transitively. This is an alternating statistic version of the “feed-forward loop” motif
AltKTrianglesC Cyclic closure. A positive parameter value indicates a tendency for directed cycles of length 3 in the network, representing non-hierarchical network closure. An alternating statistic version of the “three-node feedback loop” motif
Sender a Sender on binary attribute a. A positive parameter value indicates that nodes with the attribute are more likely to have an incident arc directed from them
Receiver a Receiver on binary attribute a. A positive parameter value indicates that nodes with the attribute are more likely to have an incident arc directed to them
Interaction a Interaction on binary attribute a. A positive parameter value indicates that two nodes which both have the attribute are more likely to have an arc directly connecting them
Matching c Matching on categorical attribute c. A positive parameter value indicates that two nodes which have the same value of the attribute are more likely to have an arc directly connecting them
Loop Self-edge. A positive parameter value indicates a tendency for self-edges (loops)