Urban Agglomeration and Inter-city Innovation Collaboration

The initial sample consists of panel data at the city-pair level from 2010 to 2022 in China. The raw patent data is sourced from the China National Intellectual Property Administration's database. Urban agglomeration policy data is manually compiled by reviewing official documents, including urban agglomeration development plans from the State Council and National Development and Reform Commission. Nighttime light data is obtained from the NPP-VIIRS dataset. Control variables are primarily from the China City Statistical Yearbook, individual city statistical yearbooks, and the China Stock Market & Accounting Research (CSMAR) database. Only observations with no missing values for the main variables are retained, and the top and bottom 1% and 99% of all continuous variables are winsorized. After these treatments, the final sample includes 379,084 city-pair-year observations.