is given to the source.

This paper was originally written as one of the reports for the project “The choice between formal and informal intellectual property, ” funded by the UK Intellectual Property Office. We are grateful to Christian Helmers and the late Mark Rogers for their participation in the project and the data construction.We have received useful comments from participants in the CDM Workshop, London, December 2013and various seminars. This work contains statistical data from UK ONS which is Crown copyrightand reproduced with the permission of the controller of HMSO and Queen’s Printer for Scotland. Theuse of the ONS statistical data in this work does not imply the endorsement of the ONS in relationto the interpretation or analysis of the statistical data. This work uses research datasets which maynot exactly reproduce National Statistics aggregates. The views expressed herein are those of the authorsand do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peer-reviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications