DO PATENT POOLS ENCOURAGE INNOVATION? EVIDENCE ...
DO PATENT POOLS ENCOURAGE INNOVATION? EVIDENCE ...
DO PATENT POOLS ENCOURAGE INNOVATION? EVIDENCE ...
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TABLE 10: VARIATION IN LICENSING<br />
OLS– DEPENDENT VARIABLE IS <strong>PATENT</strong>S PER SUBCLASS AND YEAR<br />
All Patents<br />
Pool<br />
Subclasses<br />
Only<br />
Cited<br />
Patents<br />
Only<br />
Fixedeffects<br />
Poisson<br />
(1) (2) (3) (4) (5)<br />
Pool*pool patents -0.248 -0.395* -0.366* -0.096 -0.068**<br />
(0.155) (0.175) (0.183) (0.072) (0.015)<br />
Pool*pool patents*1-5 licensees -0.222 -0.162 -0.165 -0.143 -0.124**<br />
(0.234) (0.226) (0.230) (0.084) (0.036)<br />
Pool*pool patents*>5 licensees -0.174 -0.069 -0.072 -0.137 -0.094<br />
(0.236) (0.231) (0.235) (0.125) (0.068)<br />
Constant 0.947** 0.947** 2.003** 0.457**<br />
(0.008) (0.008) (0.090) (0.005)<br />
Subclass fixed effects Yes Yes Yes Yes Yes<br />
Year fixed effects Yes Yes Yes Yes Yes<br />
Linear and quadratic trends - Yes Yes Yes Yes<br />
Standard errors clustered at the subclass level; ** significant at 1 percent, * significant at 5 percent.<br />
N (# of subclasses * 28 years) 1,285,676 1,285,676 25,340 1,285,676 1,285,676<br />
R-squared 0.526 0.526 0.529 0.497<br />
Notes: Data include 45,917 subclasses in 103 main classes that include at least one pool patent. The timing of<br />
invention is measured by the year of the patent application. The variable pool equals 1 for years after the pool<br />
forms. Pool patents counts patents that were included in the initial pooling agreement and list subclass c as<br />
primary (original) subclass. Cross-reference patents counts patents that list subclass c as a secondary (crossreference)<br />
subclass. Pool subclass equals 1 for 371 subclasses that include at least one pool patent; crossreference<br />
subclass equals 1 for 534 subclasses that include at least one cross-reference patent. Column (3)<br />
restricts the data set to subclasses that are listed either as primary or secondary (cross-reference) subclass for<br />
patents that were included in the initial pool agreement. Cited patents restricts the data set to 298,503 of<br />
472,303 patents that are cited by at least one U.S. patent between 1920 and 2002.<br />
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