***** To join INSNA, visit http://www.insna.org *****
Not exactly sure what you mean by this, but there are many methods of over time analysis. The biggest issue is the data and the research question. If you are interested in identifying behaviors that drive network evolution, you can use Siena and there is a new time test for heterogeneity (Lospinoso et al, 2010).  
 
Siena is agency-oriented while the evolution of networks takes place at the systems level. The networked system evolves in terms of a large possible sets of interactions and recursions. (Anticipations are additionally possible.)
 
At each moment of time one has a network which can also be written as a matrix. Over time, one thus obtains a set of stracked matrices. The formal description of the evolution in the network would assume solving a set of partial differential equations. The problem is usually not analytically solvable, and the issue is thus how to approach it.
 
In the dynamic version of visone, time is used as another variant and the stress-minimalization is extended from two to three dimensions. Instead of reducing (Kruskall's) stress at each moment of time, one can also reduce stress in relation to preceding or subsequent years. When more years are included, the animation becomes more stable (Baur & Schank, 2008; Leydesdorff & Schank, 2008). This solution has become possible because of optimizing the majorant (Erten et al., 2004; Gansner et al., 2005).
I understood that there is also a solution to the problem in ORA. Pajek2SVG uses interpolation between the years. In Sonia, new nodes are not positioned in anticipation to the next year.
 
Best wishes,
Loet
 
References:

Baur, M. & Schank, T., 2008. Dynamic Graph Drawing in Visone. Technical University Karlsruhe, Karlsruhe. Available at http://digbib.ubka.uni-karlsruhe.de/volltexte/1000007990 (Retrieved on  June 18,  2010).

Erten, C., Harding, Ph. J.,  Kobourov, S. G., Wampler, K., & Yee, G. V. (2004). GraphAEL: Graph animations with evolving layouts. Pages 98-110 in Liotta, G., Editor, Graph Drawing, Perugia, Italy, September 21-24, 2003; Springer, 2004. 

Gansner, E. R., Koren, Y., & North, S. (2005). Graph Drawing by Stress Majorization. In J. Pach (Ed.), Graph Drawing, Lecture Notes in Computer Science (Vol. 3383, pp. 239-250). Berlin/Heidelberg: Springer.

Leydesdorff, L., & Schank, T. 2008. Dynamic Animations of Journal Maps: Indicators of Structural Change and Interdisciplinary Developments. Journal of the American Society for Information Science and Technology, 59(11), 1810-1818.

 

 

 If you want to compare two networks in time to see if they are different, you can use an ERGM with edgecov term for the earlier network. If you have a lot more data as in email networks, you can monitor/plot various network statistics over time, or to be more sophisticated, you can assume a range of typical behavior and use SPC methods to detect departures from this over time (McCulloh, 2009). Again with enough data, Fourier Analysis can be used to identify significant periodic trends in network statistics (McCulloh, Johnson, Carley, n.d.) which can be used to fine tune assumptions in SPC approaches. SPC approaches can also be useful for exploring area of time heterogeneity when Siena models won't converge. Jaccard Index can also be used to determine network change along with Hamming and Euclidean distance. Another approach that is somewhat controversial is to compare triad census of networks, but suppose you could really compare many different network statistics over time. This is why the research question is so important.

Hope this helps.

Ian

Sent via BlackBerry by AT&T


From: "Loet Leydesdorff" <[log in to unmask]>
Date: Thu, 17 Jun 2010 13:50:20 +0200
To: 'Ian McCulloh'<[log in to unmask]>; <[log in to unmask]>
Subject: RE: How to visualize the evolution of social network?

Yes, the issue is whether there is a statistics for controling change as an alternative to comparative statics (with interpolation).
 
Best, Loet
 

Loet Leydesdorff
Amsterdam School of Communications Research (ASCoR),
Kloveniersburgwal 48, 1012 CX Amsterdam.
Tel.: +31-20- 525 6598; fax: +31-20- 525 3681
[log in to unmask] ; http://www.leydesdorff.net/

 

 


From: Social Networks Discussion Forum [mailto:[log in to unmask]] On Behalf Of Ian McCulloh
Sent: Thursday, June 17, 2010 1:14 PM
To: [log in to unmask]
Subject: Re: How to visualize the evolution of social network?

***** To join INSNA, visit http://www.insna.org ***** ORA has network visualizations over time.  It also has features such as statistical process control to detect changes over time, Fourier analysis to identify periodicity in over time data.  ORA is freely available at www.casos.cmu.edu.

2010/6/17 <[log in to unmask]>
***** To join INSNA, visit http://www.insna.org ***** I have a small online social network embedded with the time variable on the second scale.
Does anyone know any software dealing with the visualization of the network evolution? 
I 've tried Pajek and UCINET, both of which could only draw the network graph temporally.

Thanks for your generous help. 

ZHANG Lun
PhD Candidate,
City University of Hong Kong  
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_____________________________________________________________________ SOCNET is a service of INSNA, the professional association for social network researchers (http://www.insna.org). To unsubscribe, send an email message to [log in to unmask] containing the line UNSUBSCRIBE SOCNET in the body of the message. _____________________________________________________________________ SOCNET is a service of INSNA, the professional association for social network researchers (http://www.insna.org). To unsubscribe, send an email message to [log in to unmask] containing the line UNSUBSCRIBE SOCNET in the body of the message.