# Table 1

Study definitions
Term Definition
Alter A member of the network with whom another member of the network shares knowledge, an IPs communication contacts [here, used only in the definition of eigenvector centrality].
Authority A member of the network that receives communication from many hubs. This person receives information from potentially important people in the network.
Betweenness Centrality How often a member of the network falls between the shortest knowledge-sharing path of two other members of the network. For example, if two IPs have a mutual contact but cannot, themselves, communicate with one another, their mutual contact serves as a broker of communication, a network node with high betweenness, as he or she falls within the shortest communication path between the other two network members.
Bridge A node connected to a diverse set of other nodes
Centralization How much the network is centered around a few central members.
Clique A subgroup of members of the network in which each person is connected to every other member of the subgroup.
Component A sub-group that was not connected to any sub-group in the network.
Constraint A measure of bridging: low constraint indicates connection to others who are not themselves connected.
Eigenvector Centrality The relative number of knowledge-sharing episodes of a particular member of the networks alters. For example, if an IP#1 has one alter (IP#2) who themselves has one alter (IP#3), the maximum amount of knowledge that can be gained by IP#1 is, at most, the sum of the knowledge of IP#2 and IP#3 (low eigenvector centrality for IP#1). However, if IP#2 has 80 contacts, the knowledge potential through the IP#1 to IP#2 communication path is much greater since IP#2 has a lot of different communication paths with which to obtain information (high eigenvector centrality).
Fragmentation Key Player A member of the network capable of holding the network together in as few components as possible while taking into account the size of each component as well as the other fragmentation key players. This is an IP that, if removed can break up the network into many pieces, cutting off certain members from obtaining information from the rest of the network.
Hub A member of the network that provide information many authorities. These members provide information to potentially important members of the network.
In-degree Centrality The number of times a member of the network was asked for knowledge.
Isolate A member of the network with no connections to any other member of the network.
Knowledge Sharing Having exchanged infection prevention-related information formally or informally via any method with another member of the network in Iowa over the past 6â€‰months.
Node A survey respondent.
Out-degree Centrality The number of times a member of the network asked another member of the network for knowledge.
Reach Key Player A member of the network that had the capability of sharing knowledge with the largest proportion of other nodes in the network while taking into account the other reach key players and the potential for redundant connections. This is an IP that has a lot of contacts that other members of the network do not share, making them a unique individual with respect to the number of other members of the network with which they can communicate.

Wiemken et al.

Wiemken et al. BMC Research Notes 2012 5:387   doi:10.1186/1756-0500-5-387