[statnet_help] fragmented bipartite network...

[Carter T. Butts]

Hi, Harald -

Coexistence of large complex components does not generally occur unless 
something drives the fragmentation, and this is what your models are 
telling you: the terms you are currently using do not include the forces 
that are sufficient to reproduce your component size distribution.  That 
means that you need to think about why your network is split into 
fragments, and include terms that capture the relevant social forces.  
Thinking about likely mechanisms is step zero, so do that before 
anything else!  Guided by your substantive knowledge of what is likely 
going on, you will next (as others have said) want to look at covariate 
effects relating to differential mixing, since those are your most 
obvious and most important sources of heterogeneity.  If you find that 
there is still more fragmentation that can be explained by other means, 
you may need to consider model terms relating directly to component 
count or size.  These are still somewhat experimental, and are currently 
sequestered in an add-on package called ergm.components 
(https://github.com/statnet/ergm.components). However, this package can 
be installed from github (see the github page), and the terms will work 
automagically with ergm() and friends once the package is loaded.  
Depending on your situation, you may need or want to examine the 
components() or compsizesum() terms, both of which are documented within 
the package.

Hope that helps,

-Carter

On 11/30/23 9:58 AM, Harald Waxenecker wrote:

>

> Dear ‘statnet community’,

>

> Our research focuses on tie formation and elite cohesion, specifically 

> examining interlocking directorates and kinship relations. The 

> dependent bipartite business network comprises 6,902 individuals and 

> 5,178 companies, exhibiting sparsity (density = 0.00012) and 

> fragmentation with 4,455 components, including 3,850 isolates in the 

> first mode (persons). The attached documents contain descriptives and 

> the component size distribution from the observed network.

>

> The fragmented structure is important, as other network layers, like 

> kinship relations, are expected to contribute to the cohesion of this 

> business network. We apply ERGM to model these processes, but we 

> struggle to capture the fragmented structure of the observed network. 

> The component size distribution of the simulated network differs 

> significantly. In addition, the goodness-of-fit (GOF) for k-stars (in 

> both modes) and geodesic distances (Inf) shows significant results. 

> All these results are also attached.

>

> We've explored various options, including constraints, MCMC 

> propositions, and simulated annealing, but haven't achieved success. 

> Please, we would like to ask for your help to improve our model. Thank 

> you!

>

> Kind regards,

>

> Harald

>

> ---

>

> *Harald Waxenecker

>

> *

>

> *Masaryk University | Faculty of social studies*

> Department of Environment Studies

> A: Jostova 10 | 602 00 Brno | Czech Republic

> E: waxenecker at fss.muni.cz <mailto:waxenecker at fss.muni.cz>

>

>

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