Measuring knowledge spillovers: What patents, licenses and publications reveal about innovation diffusion

Measurement of knowledge spillovers remains an important challenge. While patent citation analyses are one common empirical approach, questions persist about their efficacy and potential biases. In an effort to assess various measures of knowledge diffusion, this paper compares patent data surrounding recombinant DNA technology to licenses and publications building on the same technology. Evaluation of these measures highlights errors of both omission and over-representation in each measure, and reveals potential biases tied to organizational age and location. The results suggest that studies of knowledge diffusion can be strengthened dramatically by drawing upon multiple indicators. (C) 2009 Elsevier B.V. All rights reserved.