Previous research studies the age profile of patent citations to learn about knowledge flows over time. However, identification is problematic because of the collinearity between application year, citation year, and patent age. We show empirically that a patent's ‘citation clock’ does not start until it issues, and propose a highly flexible identification strategy that uses the lag between application and grant as a source of exogenous variation. We examine the potential bias if our assumptions are incorrect, and discuss extensions into other research areas. Finally, we use our method to re-examine prior results on citation age profiles of patents from different technological fields and application year cohorts. Copyright (C) 2009 John Wiley & Sons, Ltd.

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This article uses citations to patents disclosed in the standard setting process to measure the technological significance of voluntary standard setting organizations (SSOs). We find that SSO patents are outliers in several dimensions and importantly, are cited far more frequently than a set of control patents. More surprisingly, we find that SSO patents receive citations for a much longer period of time. Furthermore, we find a significant correlation between citation and the disclosure of a patent to an SSO, which may imply a marginal impact of disclosure. These results provide the first empirical look at patents disclosed to SSO’s, and show that these organizations both select important technologies and play a role in establishing their significance.

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