Patent survival analysis of China´s communication industry

Based on China´s patent data of communication industry from 1985 to 2009, and using the term of patent right as the measurement of patent value, this paper presents a survival function of patent maintenance in China and stratified Cox regression model. It makes a comparison study in terms of four aspects: the quality of domestic and foreign patent applicants, different technical fields, different types of Chinese applicants and different time periods. The result shows that there is a large gap in patent quality between domestic and foreign patent applicant. With regard to technical fields, there is important difference. Among all the Chinese applicants, patents filed by firms command higher quality; those by individual possess lower quality, but not lower than those filed by research institutions. About time periods, it is no doubt that patent quantity is much better in later than in previous years.