Previous work studying the age distribution of citations for patents relies on functional form assumptions to address the co-linearity between the birth year, citation year, and age. This paper proposes a non-parametric identification strategy that uses the lag between application and grant as a...

A growing body of research uses patent citations to analyze economic phenomena, and many of these papers are interested in the distribution of citations over the life of a patent. However, this question leads directly to the age-year-cohort identification problem, i.e. co-linearity between the...