My colleague and I are looking to use SNA to look at the risk of contact between an intermediate and definitive host of a parasite. We have built a bipartite network where one set of nodes consist of locations where intermediate hosts reside (and which we have data on abundance) and the other set of nodes consist of the definitive hosts that are connected to the location nodes based on presence/absence from field surveys. The edges in the network are weighted based on abundance of intermediate hosts and the distance definitive hosts are from the location. The initial idea was to identify which locations had the greatest influence in terms of contact between intermediate and definitive hosts, using either normalised (weighted) degree or centrality. However, to do this we understand that the network would need to be projected into a unipartite network – the rationale for connecting locations in a project networks seems theoretically wrong for our purpose. Are there other approaches that can directly calculate normalised degree in a weighted bipartite network without the need to project the network?
Dear Bryony Tolhurst,
I think your research setting sounds very interesting. However, I'm not sure that I really understand your statement that "the rationale for connecting locations in a project networks seems theoretically wrong..." since the intermediate hosts can be seen as "brokers" connecting different locations/definite hosts (I wrote a paper on broker roles and social capital which is here on research gate which might be of interest to you)? Maybe you canelaborate a little on this... Or do you see "definit hosts as isolated actors?
Kind regards, Volker
Hi Volker
Thank you so much for your response. Yes please I would be interested in the broker rules paper you refer to - is it the book chapter on 'Local Social Capital in Unfolding Social Structures'? I have downloaded it and will read it.
To elaborate, our two types of nodes in the network are individual dogs (definitive host) and quadrats for which we sampled gastropods [various slug and snail species] (for our intermediate host). We don't see the dogs as isolated actors but we are not interested in contacts between a) dogs and each other and b) gastropods and each other. Does that make sense? We don't have observed contacts between gastropods and dogs but we do have data on where and when and how many each of gastropods (in quadrats) and dogs (recorded from point count locations in the same area as the quadrats) occur in specific sites and habitats. We assume that the more there are of each of dogs and gastropods in the same types of sites, habitats and timescales, the more likely they are to come into contact. We haven't actually observed them coming into contact but we know it happens and that when it does it may result in transmission of lungworm. Do you see?
Many thanks for your time
Bryony
Dear Bryony,
I would refer you to my paper on „measuring the social capital of broker roles“; you might also want to look at Ronald Burt‘s book on „brokerage and closure“...
Hope this is of any help to you - good luck.
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