Abstract
Although labor mobility has been recognized as a key mechanism for transferring tacit knowledge, prior research on inventors has so far hardly discussed the impact of a move on inventive performance. Additionally, existing research has neglected the differences in gains from a move between high and lower performing inventors. This paper adds to the current R&D literature by presenting a jointly estimated quantile regression to compare the coefficients of the explanatory variables at different points of the performance distribution. Additionally, dummy variables are used to compare inventive performance prior and in the aftermath of a move. Results reveal that inventors at the upper end of the performance distribution are better able to benefit from a move to draw level with or to overtake non-movers in the post-move period. Whereas at the bottom of the performance distribution a higher level of education has a positive impact on inventive performance, education does not matter significantly at the upper end of the performance distribution. Data for the analysis was derived from a survey of German inventors (N = 3,049).
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Notes
In the following study, a move of an inventor is defined as a change of employer.
Ex-ante means at the time of the patent application.
PatVal is the acronym for “The Value of European Patents: Empirical Models and Policy Implications Based on a Survey of European Inventors.”
See Giuri et al. (2007) for a detailed description of the PatVal-EU survey results.
The sample of 10,500 patents includes all opposed patents (1,048) and patents which were not opposed but received at least one citation (5,333), and a random sample of 4,119 patents drawn from the remaining 9,212 patents.
The lower limit (1985) was chosen, since the years between 1977 and 1984 are characterized by a strong increase in the number of European patent applications, which was caused by the diffusion of the European patent after the founding of the EPO in 1978. Hence, I assume that as of mid-1980, European patent data are a sufficiently reliable source of data to use for an empirical analysis. The upper limit (1999) was chosen due to the limitations in the availability of citation data. To count the number of citations a patent received from subsequent patents and to compare citations between patents applied for in different years, the number of citations received within a 4 year time lag from the publication of the search report was employed. Since the search report is published about one year after a firm or an individual inventor applied for the EP patent, patent data as of 2004 are needed to calculate 4 years citation lags for patents with priority year 1999.
For more information about the name matching procedure, see Hoisl (2007a).
For a more detailed description of the bootstrap percentile method, see Hahn (1995).
As a robustness check, the performance of the inventor before and after a selected move relative to a control group was analyzed using a difference-in-differences (DiD) approach. To measure inventive performance quantity measures (number of patents per inventor) as well as quality measures (grant rate, rate of withdrawal, rate of refusal, opposition rate, and number of citations) were employed. Results show that the number of applications does not change due to the move. However, the incident of a move has a positive impact on the mean share of applications granted. Furthermore, a move seems to have no impact on the share of patents refused by the patent examiner. In case the share of patent applications withdrawn by the applicant is considered, a move has a negative impact. Whereas the share of withdrawals prior to the move is larger for the movers than for the control group, it becomes smaller afterwards. The share of oppositions received within the opposition term of nine months after the patent was granted is lower in the movers’ group before the move took place and higher afterwards. According to Harhoff and Hall (2003, unpublished manuscript), the number of oppositions a patent received is a proxy for the value of the patent. Opposition results hence confirm that patent applications of the mobile inventors become more important after the move. In addition, citation counts also underline the proposition that a move has a positive effect on the value of after-move patent applications. The DiD estimator indicates that the number of citations increased after the move. The latter finding is consistent with the results described in this paper.
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Acknowledgements
I would like to thank the conference audience at the 33rd Conference of E.A.R.I.E. in August 2006, the conference audience at the 1st Annual Conference of the EPIP Association “Policy, Law and Economics of Intellectual Property” in September 2006, and the audience at the DRUID Summer Conference in June 2007 for helpful comments. Special thanks go to Dietmar Harhoff, Jesse Giummo, Marc Gruber, Pierre Mohnen, Mark Schankerman and an anonymous referee for their valuable comments. The survey responses used in this analysis originate from a coordinated survey effort in Italy, France, Spain, the Netherlands, the United Kingdom and Germany. The author thanks the European Commission, Contract N. HPV2–CT-2001-00013, for supporting the creation of the joint dataset. This paper makes use of the German survey responses. The usual caveat applies.
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Hoisl, K. Does mobility increase the productivity of inventors?. J Technol Transf 34, 212–225 (2009). https://doi.org/10.1007/s10961-007-9068-5
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DOI: https://doi.org/10.1007/s10961-007-9068-5