Changes

The answer to connecting the Patent database to the Assignment database lies somewhere in using the information in the table DOCUMENT_INFO to connect to a patent_id from the Patent database PATENT table for each assignment in the Assignment database ASSIGNMENT table. On further investigation into "The USPTO Patent Assignment Dataset: Descriptions and Analysis, the field they called "grant_doc_num" (grant_num above) in DOCUMENT_INFO is the patent number (the description of DOCUMENT_INFO above has been altered to reflect this.)

The paper mentions that there will errors in patent number stored in DOCUMENT_INFO under grant_doc_num so a separate table called DOCUMENT_INFO_ADMIN was constructed to determine how prevalent errors were. They queried the patent number from for the appno_doc_num from administrative data. The "appno_doc_num" is the Application Document USPTO number from DOCUMENT_INFO. On further investigation into the paper, it became clear that "administrative data" refers to internal USPTO data that was available to the authors of the paper, but that we might not have. However, in 99% of cases the grant_doc_num and the queried patent number based on the appno_doc_num were the same, so we can probably rely on grant_doc. Therefore, since every table in the Patent database will have the patent number stored, to connect any table in Assignment to the Patent database, it would first be joined with DOCUMENT_INFO on rf_id and then joined with the appropriate table in Patent on patent number.