Table 2.

Description of total and regional networks

	Knowing each other	Having professional contact
	Total network	Total network	Area one	Area two	Area three
Number of health professionals	101	101	28	32	41
Total number of connections (ties)	1,431	664	113	91	158
Reciprocity	0.630	0.479	0.614	0.400	0.547
Density	0.142	0.066	0.139	0.092	0.146
Clustering (weighted)	0.360	0.268	0.344	0.253	0.395
Transitivity (three legs in triads with two legs)	16.7%	13.3%	16.9%	12.4%	20.9%
Indegree centralization of network	25.1%	16.6%	22.6%	10.5%	26.5%
Outdegree centralization of network	22.1%	16.6%	33.7%	27.2%	19.2%

Reciprocity: Proportion of all connections that are reciprocated. The measure is used as an indicator of the reliability of the measurement of connections.

Density: Proportion of all possible connections that are actually present in a network of a given size.

Clustering: Average density in the local neighborhoods of individuals rather than in the total network. Here it is defined as the density in the networks of others connected to an individual (leaving out ego in the calculation of density). The average value is weighted for size of network.

Transitivity: Measure related to triads that may indicate balance or equilibrium. If A directs a tie to B and B directs a tie to C, then A is also expected to direct to C. Triads are crucial in some social science theories.

Centralization of network: Degree of variance of the total network of (in/out going) connections compared to a perfect star network of the same size (which indicates the theoretical maximum of centralization). Higher values mean more centralization, thus that positional advantages are unequally distributed.