2.3.1. Data Source

This study used the listed enterprises in the field of new energy vehicle industry as the research object. China's support policies for the new energy vehicle industry began to grow rapidly after 2010. In this study, enterprises listed on energy vehicles from 2010 to 2019 were selected as the research samples, and the samples were processed as follows: (1) the samples with ST and ST\* marks were excluded; and (2) eliminated samples with missing data. Finally, we obtained 242 new energy automobile enterprises, with a total of 1671 observations. To prevent interference from extreme values, all continuous variables were subjected to tailing reduction.

The patent data for this study came from the Incopat database. First, the name of each listed company and its subsidiaries was extracted from the Chinese Research Data Services (CNRDS) database. Then, the names of the listed companies and their subsidiaries were manually retrieved by patent applicants through the Incopat database, and the patent data of the listed companies and their affiliates were counted. Finally, the number and quality data of patents applied for by enterprises every year were obtained through sorting and statistics. Government subsidies and other financial data received by the enterprises were obtained from the Wind and CSMAR databases.
