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) |