In many countries holders of patents must pay an annual renewal fee in order to keep their patents in force. This paper uses data on the proportion of patents renewed, and the renewal fees faced by, post World War II cohorts of patents in France, the United Kingdom, and Germany, in conjunction...

The purpose of this paper is to present and estimate a model which allows one to use the recently computerized U.S. Patent Office's data base to identify when and where changes in inventive output have occurred. The model assumes a firm which chooses a research strategy to maximize the expected...