Geography Reference
In-Depth Information
Table 16
.
3
Network of inventors: size of selected components; selected years*
No. of inventors
% of inventors (excl. isolates)
1991 (no
.
of components = 2525)
Principal component
3664
23.39
2nd largest
"
287
1.83
Smallest
"
2
0.01
1995 (no
.
of components = 2969)
Principal component
7038
33.29
2nd largest
"
250
1.18
Smallest
"
2
0.01
1999 (no
.
of components = 3595)
Principal component
14077
45.97
2nd largest
"
277
0.90
Smallest
"
2
0.01
Notes:
* Each year's network is calculated by taking into account all patent applications for the selected
technological classes over the previous i ve years.
Table 16
.
4
Concentration of inventors, by MSA; principal network component, selected
years
Year
No. of
inventors
a
No. of active
inventors
b
No. of MSAs with
active inventors
% of active
investors in top
5 MSAs
c
1991
3664
1509
59
59.2
1995
7038
2934
80
52.0
1999
14077
5656
103
53.8
Notes:
a
No. of inventors in the principal component of the inventors' network. Each year's network is calculated
by taking into account all patent applications for the selected technological classes over the previous i ve
years.
b
No. of inventors in the network having signed at least one patent application in the given year, for the
selected technological classes.
c
Top i ve MSAs: San Francisco, New York, Baltimore, Philadelphia, Boston.
4.
The role of 'movers', and their social ties
Sampling
Following as closely as possible the JTH methodology, as adapted by Agrawal et al.
(2006), we selected for this study three cohorts of
originating
patents, consisting respec-
tively of the 1991, 1992 and 1993 patent applications that received at least one subse-
quent citation by the end of 1999.
13
For each cohort of originating patents, we eliminated all applications that either
received citations only from foreign organizations, or whose applicant was a US
