MIT has released its 2004 “Technology Scorecard” (Excel) ranking U.S. patent portfolios of 150 technology companies in eight sectors. Ranks are based on the number of patents, patent citations, scientific paper citations, and technology cycle time. Pfizer and Delphi topped their respective sectors.
Adam Jaffe has done quite a bit of work in this area and has promoted the use of patent citation data as a proxy for patent quality and knowledge transfer.