Networks and link data, was preprint version "Globalisation in science in 2005"

[David E. Wojick]

Thank you Christina, very useful.

Most network analysis is quite rightly focused on networks for which 
we have link data. I am interested in, and took Loet to be talking 
about, some more basic network of scientists, about which we have 
very limited data. It is this concept, that there is an existing 
network to be discovered, that drives us to seek new kinds of data.

More especially, I am trying to study diffusion of thinking among 
scientists at a level for which there may be no individual link data. 
Message by message transactions if you like. This is analogous to 
diffusion of groundwater, where we know we cannot track individual 
molecules. In the case of water we monitor pressure using a 3D grid 
of sensors. In my case I am looking at the migration of new language 
in, say, journals, or proposals, or conference proceedings.

The math of discrete network analysis may or may not apply in my 
cases. How to bridge the gap between discrete network analysis and 
diffusion seems to me to be an important question. I think a similar 
problem arises in statistical mechanics.

David Wojick


For my own learning process, let me try to respond to your original 
questions, and then maybe the more experienced on the list can 
correct me.
>My first question is, does every initial transaction between two 
>people, no matter how slight, establish a link in the network? The 
>alternative might be that certain thresholds of interaction must 
>apply, such as co-authorship or citation. My second question is, do 
>you think that the strength of a link might usefully be measured by 
>the amount of information that passes between the people linked?

Network analysis works on relationships as the basic unit (not 
attributes, for example).  How these relationships are 
defined/determined depends on what makes sense for the system being 
studied.  We can look at co-authorship, co-citation, co-membership 
(in an organization) or a 2-mode thing like co-attendees of an 
event...  So we might look at co-authorship of only peer reviewed 
journal articles that are in journals indexed by ISI -- which sets 
the bar fairly high.  For things like co-authorship, the relationship 
is non-directional but can be valued.  It can have different weights 
for the number of times the authors appear together if that makes 
sense to the phenomenon you are studying.  Many times, it makes more 
sense to just have 1s and 0s -- link or no link.  As for amount of 
information, one of the problems in network analysis is obtaining the 
data.  Can you interview everyone involved?  How much information can 
you obtain about the actors?  Can that information be easily made 
into a matrix for mathematical operations?  I think there's the 
pragmatic aspect of what is do-able as well as the science aspect of 
what you want to look at.

The standard book on SNA is Faust and Wasserman and there have been 
several relevant chapters in ARIST on citation analysis, but you 
might do best by reading Dr. Leydesdorff's books and web page.

Christina K. Pikas, MLS
R.E. Gibson Library & Information Center
The Johns Hopkins University Applied Physics Laboratory
Voice  240.228.4812 (Washington), 443.778.4812 (Baltimore)
Fax 443.778.5353

-- 

"David E. Wojick, Ph.D." <WojickD at osti.gov>
Senior Consultant -- The DOE Science Accelerator 
http://www.osti.gov/innovation/scienceaccelerator.pdf
http://www.osti.gov/innovation/
A strategic initiative of the Office of Scientific and Technical 
Information, US Department of Energy

(540) 858-3150
391 Flickertail Lane, Star Tannery, VA 22654 USA
http://www.bydesign.com/powervision/resume.html provides my bio and 
client list.
http://www.bydesign.com/powervision/Mathematics_Philosophy_Science/ 
presents some of my own research on information structure and 
dynamics.

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