Geography Reference
In-Depth Information
to, or an understanding of, that algorithm, rivals could see the components of the knowl-
edge in the patent but not how the components worked together. As a result, competi-
tors faced an uphill battle in exploiting the knowledge. Even within the i rm, ef ective
transmission required the inventor to travel around the country to teach others how to
use the technology. Similarly, competitors found it dii cult to reproduce IBM's copper
interconnect technology - another invention of intermediate complexity - until enough
engineers defected to rivals to dif use the relevant knowledge of how to fabricate the
copper interconnect without contaminating the wafer's other materials (Lim, 2009).
By comparison, inventions involving extremely high levels of interdependence defy
dif usion even within a social boundary. Plasmid preparation, for example, a biologi-
cal technique, involves an intricately intertwined sequence of actions involving various
chemicals, reagents and manual operations. As Jordan and Lynch (1992, p. 84) note,
'Although the plasma prep is far from controversial and is commonly referenced as a
well established and indispensable technique, how exactly it is done is not ef ectively
communicated, either by print, word of mouth, or demonstration.' On the other hand,
inventions involving a low degree of interdependence dif use rapidly. For instance,
patent #4,927,016, one of the patents in the bottom quartile of the
k
range, involves the
production of monoclonal antibodies. The industry associated with this technology has
essentially become a commodity business since one can easily acquire all the necessary
knowledge components by reading a textbook and piece them together without concern
for sensitive interdependencies. Polymerase chain reaction, a technique for amplifying
DNA sequences, has followed a similar route. Or, one might think of Sun's workstation
technology. The modular design of its system has allowed rivals to match the perform-
ance of its hardware quickly, limiting the company's ability to maintain an advantage in
the hardware market.
Social proximity
The analyses investigate the ef ect of knowledge complexity on the dif usion of knowl-
edge to individuals whose close social connections to the source of knowledge give them
better access to the template than individuals with distant or no connections have. For
each of our 72,801 patent dyads, we develop one direct and two indirect indicators of
social proximity between the inventors of the two patents in the dyad.
Proximity in a collaboration network
Our most direct indicator measures the distance
between inventors in a network of patent collaborators. The idea underlying this indi-
cator is that an inventor gains access to a template via collaborators, collaborators of
collaborators, collaborators of collaborators' collaborators, and so forth. Closer connec-
tions grant better access. To measure collaborative proximity, we use the methods and
data of Singh (2005).
10
Consider the dyad consisting of patent
i
issued in May or June of
1990 and patent
j
issued at a later time
t
(before 1996). To compute the distance between
i
and
j
, Singh i rst constructs a network with a node for each discrete inventor who has
been listed on any patent from 1975 until time
t
. An edge connects two inventors if they
have collaborated on a patent during that period. The collaborative distance of a patent
dyad is then the minimum number of intermediaries required to connect a member of the
team of inventors listed on patent
i
to a member of patent
j
's team. If the two teams share
a member, for instance, the distance is zero. If the teams have no common members but
