Table 4 Variable names and definitions

Dependent variable

dciting	Normalized forward-citation intensity defined by the difference between the actual number of citations received per patent and the reference citation intensity for each technological category in year t. Refer to the text for further details.

Independent variables
Single assignee
corp	Dummy variable that takes on the value of unity if the single assignee of a patent is a corporation, otherwise zero.
gov	Dummy variable that takes on the value of unity if the single assignee of a patent is a government research institute, otherwise zero.
univ	Dummy variable that takes on the value of unity if the single assignee of a patent is a university, otherwise zero.
Multiple co-assignees
corp_corp	Dummy variable that takes on the value of unity if there are no less than two co-assignees are corporations and there are no other co-assignees belonging to universities and government research institutes.
corp1_gov	Dummy variable that takes on the value of unity if a corporation is the first assignee of a patent and at least one co-assignee is a government research institute and there are no other co-assignees belonging to universities, otherwise zero.
gov1_corp	Dummy variable that takes on the value of unity if a government research institute is the first assignee of a patent and at least one co-assignee is a corporation and there are no other co-assignees belonging to universities, otherwise zero.
corp1_univ	Dummy variable that takes on the value of unity if a corporation is the first assignee of a patent and at least one co-assignee is a university and there are no other co-assignees belonging to government research institutes, otherwise zero.
univ1_corp	Dummy variable that takes on the value of unity if a university is the first assignee of a patent and at least one co-assignee is a corporation and there are no other co-assignees belonging to government research institutes, otherwise zero.
Characteristics of patents
pat_scope	A proxy for "patent scope" that is defined by the total number of technological field flags of a patent. The 19 technological fields are defined by using the Japan Patent Office (2003). Refer to Table 2 for further details.
jp_only	Dummy variable that takes on the value of unity if Japan the sole country for which a patent is filed. This is a control variable for the fact that there are very few citations received by patents that are filed to the JPO alone.
science_ratio	A proxy for the extent of science-linkage for each patent defined by "the number of backward citations of non-patent articles" divided by "the total number of backward citations + 1."
Other characteristics of assignees
pat_size	Total number of patent applications filed by the first assignee per year.
listed	Dummy variable that takes on the value of unity if a patent is filed by a listed company at the date of patent filing, otherwise zero.
Policy effect (year dummy)
D99 (or D98)	Dummy variable that takes on the value of unity if the priority year is 1999 (or 1998) and later, otherwise zero. In Japan, several policy initiatives for industry-government-university cooperation in research have been implemented since 1998, as shown in Table 1.