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The Effect of Leverage Buyouts on Innovation (view source)
Revision as of 18:19, 8 December 2016
, 18:19, 8 December 2016→New Version
**Used this table to flag LBO events in Compustat dataset for appropriate gvkeys in appropriate year(s)
***Result is SQL table '''yearsbygvkeysfilled2'''
*Used USPTO patents database to tag yearly patent stocks and flows for all companies in COMPUSTAT
**Matched the list of standardized patent assignee names with list of standardized COMPUSTAT company names (links gvkey to patent assignee names); result is cross-ref table '''assigneexgvkey'''
**Used table '''patentstartend''' (which has start and end dates of when patent was active; see subsection below) and '''assigneexgvkey''' to determine, for each gvkey-year combination, the number of active patents
**Result is SQL table '''yearsbygvkeysfilled3'''
===Patent start-end table===
To construct the table of all patents and their grant dates and expiration dates (i.e., start-end of being an active patent), we did the following:
(code/detailed documentation is in <code> E:\mcnair\projects\LBO\Clean\Building the Patent Start End Table.txt</code>)
*Imported all patent maintenance fee events from the file '''MaintFeeEvents_20160613.txt'''
*Imported lookup table '''patentExpirationRules.txt''' containing patent lifetime implied by each maintenance event
*For each patent, found the latest expiration date implied by any recorded maintenance event.
==STATA analysis==
