Patent Publication and Innovation
利用1999年美国发明人保护法加速专利公开约1.5年的外生冲击，结合美欧配对专利的因果识别，发现公开加速促进了技术扩散、减少了重复研发，并促使面临更长专利授权延迟的上市公司增加4%的研发投入。
We measure how patent publication affects innovation by exploiting the American Inventor’s Protection Act of 1999 (AIPA), which accelerated public disclosure of US patents by about 1.5 years. We obtain causal estimates by comparing US patents subject to AIPA with “twin” European patents that were not. Post-AIPA, US patents receive more and faster follow-on citations, indicating greater technology diffusion. Technological overlap increases between distant but related patents and decreases between highly similar patents, and patent applications are less likely to be abandoned, suggesting less duplicative R&D. Publicly listed firms exposed to 1 standard deviation longer patent grant delays increased R&D by 4% post-AIPA.