Hall, Bronwyn H.; Jaffe, Adam; Trajtenberg, Manuel - In: RAND Journal of Economics 36 (2005) 1, pp. 16-38
We explore the usefulness of patent citations as a measure of the "importance" of a firm's patents, as indicated by the stock market valuation of the firm's intangible stock of knowledge. Using patents and citations for 1963--1995, we estimate Tobin's q equations on the ratios of R&D to assets...