This paper studies the effect of strategic patenting motives on the characteristics of a company's patent portfolios. First, we look at the frequency of change requests (``amendments'') to the originally filed claims. We expect a positive relation between patenting for exchange reasons and the incidence of amendments, since these allow the applicant to shift the exact scope of a patent application to fit the potential demand in the market for technology. Furthermore, a higher number of amendments proxies an above average effort in the application process. We expect this to be the case especially among companies using the patent system for its original protection purpose.
Subsequently, we address the relationship of amendments and forward citations. As amendments allow the applicant to incorporate knowledge gained after the original filing into the claims, amendments can result in patents of higher quality as measured by forward citations. Additionally, certain strategic patenting behavior is expected to result in higher citations not only indirectly through amendments, but also directly, since different patenting motives mirror different underlying invention characteristics.
We rely on survey data from 441 German companies as well as matched data on their respective patent portfolio including new EPO information on the application process. Using multivariate tobit models as well as two-staged least squares models, we find that firm's patenting motives are reflected in the patent portfolio in different aspects.
First, the technology exchange motive is related to a higher number of amendments, implying a strategic use of this instrument. Secondly, amendments are also associated with higher levels of citations, which suggests that they might be an instrument to raise patent quality or value. Since amendments are also partly responsible for the uncertainty in the patent system, the resulting trade-off needs to be taken into account.