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...

We find that the effects of parent firm R&D on plant-level productivity are diminished by both the geographic and technological distance between the research lab and the plants; that productivity appears to depend on R&D per plant rather than on the total amount; and that spillovers from...

The 1989 Cable Act eliminated most price regulation of cable television operators, including the right of municipalities to enforce price terms in franchise agreements. Deregulation was justified, at least partially, by the contention that competition from other entertainment media eliminated...