1. 1. For a thorough review of this literature seeBaldwin, and Scott[1987 ].
2. 2. According to Shepherd[1979 , p.400 ], '...patents are a notoriously weak measure. Most of the eighty thousand patents issued each year are worthless and are never used. Many are of moderate value and a few are bonanzas. Still others have negative social value. They are used as "blocking" patents to stop innovation, or they simply are developed to keep competition out'.
3. Innovation, Market Structure, and Firm Size