3.3. Network Characterisation
Excluding movements to abattoirs, the dataset comprised 751,003 movements. The annual average networks had 76,205 nodes and 250,334 edges. Table 3 summarises the results obtained from the exploratory network characterisation of the static networks. The annual and monthly networks were highly clustered, and their metrics were stronger in the annual networks (0.38) than in the monthly networks (0.15). The network diameter (maximum shortest path length) was 20.33 steps in the annual networks and 17.47 steps for monthly networks, meaning that a maximum of 20 steps in the annual network separated any two premises. The average number of neighbours was similar in the annual (2.61) and monthly (2.19) networks, meaning that each node in the network was connected on average to 2.6 other nodes. The shortest path length ranged from 4.29–4.47, meaning that it took approximately 4 steps to go between two randomly chosen nodes in the annual networks and between 3 and 6 steps in the monthly networks.
In the annual networks, the GWCC contained 98.49% of the active premises, meaning that trade connections reached almost all nodes. The GSCC in the annual networks contained 17.62% of the active premises and 10.17% in the monthly networks; in this subset of nodes, there was a direct path between all pairs of nodes, forming the backbone of the network and ensuring its overall connectivity.
Table 3. Summary of global metrics of the annual and monthly pig movement networks in Ecuador (2017–2019).