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 David,

Your question about what cohesion means is interesting, because it leads to
what time means. Assuming that the points in time are sparse enough to see
changes in group composition, I think analyzing the time-collapsed dataset
is an interesting idea. 

Although in that case two different processs would look the same: 

1. one set of nodes are connected only as dyadic components, at different
points in time, that looks as a cohesive group in the collapsed data

2. another set of nodes are connected into a cohesive group at one point in
time (at the same point in time).

Thanks!

Balazs

> -----Original Message-----
> From: Social Networks Discussion Forum 
> [mailto:[log in to unmask]] On Behalf Of David Gibson
> Sent: Tuesday, December 20, 2005 8:57 AM
> To: [log in to unmask]
> Subject: Re: cohesion in a dynamic network
> 
> *****  To join INSNA, visit http://www.insna.org  *****
> 
> Balazs,
> 
> First you have to ask what cohesion means in dynamic data. 
> Your formulation "common history of cohesion" would probably 
> lead most of us to simply sum instances of dyadic contact (I 
> take your data to be in some way episodic) to create a 
> time-collapsed snapshot, on which standard subgroup analyses 
> can be performed. The interesting complication is that a 
> group can be "actually" cohesive and yet not act that way 
> over shorter or longer periods, if you permit a distinction 
> between latent or propensity ties and enacted ties and 
> recognize that the latter are subject to constraints such as 
> those considered in
> 
> Gibson, David R. 2005. "Concurrency and Commitment: Network 
> Scheduling and its Consequences for Diffusion." Journal of 
> Mathematical Sociology
> 29:295-323
> 
> David
> 
> Balazs Vedres wrote:
> > *****  To join INSNA, visit http://www.insna.org  *****
> >
> > Dear Socnetters,
> >
> > I wonder if anyone had experience with identifying cohesive 
> groups in 
> > dynamic network data.
> > How would you identify a group as a common history of 
> cohesion rather 
> > than a cohesive subset in a network snapshot?
> >
> > Any comments are appreciated,
> >
> > Best
> > Balazs
> >
> > 
> _____________________________________________________________________
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> 
> -- 
> 
> David Gibson
> 
> Assistant Professor
> 
> Department of Sociology
> 
> University of Pennsylvania
> 
> 3718 Locust Walk
> 
> Philadelphia, PA 19104-6299
> 
>  
> 
> http://www.soc.upenn.edu/~gibsond/
> 
> _____________________________________________________________________
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