管理工程学报2012，Vol.26Issue(4)：77-83,7.
中国专利生存期:基于中国在美专利数据的实证
Determinants of Patent Duration: A Survival Analysis of China-Invented US Patents
摘要
Abstract
Although the number of Chinese patents around the world has been increasing, China's patent quality remains relatively low. Because of the relatively high expense of patent application in the US, people tend to believe that China-invented US patents have a high quality. The quality of the US patent applied by Chinese applicants may be reflected by patent duration. The higher patent quality, the higher value and a longer duration a patent has. This paper mainly studies the patent duration of patents applied in US by Chinese applicants, and analyzes the determinants of patent survival/duration of China-invented US patents. We had searched the US PTO Patent Database for patents filed between March 30, 1987 and September 5, 2008 and their patentees are Chinese institutions or individuals. We identified 7, 569 patents including 6216 patents for inventions and 278 expired patents. Based upon the 278 US patents applied by and granted to Chinese applicants, this paper examined the relationship between patent duration and variables, including the number of forward cites, the number of backward cites (literature and patent citing) , the number of patent inventors, the nature of patentees (individual or cooperation) , the number of US patent classifications, the number of international patent classifications, and the size of patent families. We mainly use descriptive statistics, ANOVA, Kaplan-Meier survival function analysis, and COX model regression analysis. The COX model regression result suggests that; 1) If FAM (the number of patent family) increases by one, the hazard of patent expiration will significantly (p =0. 001) drop by about 8% ; 2) If CITL (the number of cited literature in the patent) increases by one, the hazard of patent expiration will significantly (p = . 051) drop by about 3. 8% ; 3) If ASCO = 1 ( Cooperation patent) , the hazard of patent expiration will drop by about 27% without significant result (p = 0. 127); 4) If ASP = 1 (Individual application) , the hazard of patent expiration will significantly (p =0. 008) drop by about 32% ; 5) There is no significant relationship between CITD, IVNO, CAT, IPCNO and patent duration. This finding suggests that if FAM (patent family) or CITL (cited literature) increases, the patent duration will be longer. In addition, the cooperation patents have a longer patent duration, as well as CITD ( Number of been cited) , IVNO ( Number of inventors) , CAT ( Number of US patent classifications) , and IPCNO (Number of IPCs) have no significant relationship with the patent duration. This study can help investor judge the real value of a patent and provide new evidence for the current literature on patent duration. However, due to limited sample size and the difficulty in data acquisition, this paper does not include such data as the number of patent claims and patent audit. Future study may want to further investigate China-invented patents by increasing the sample size and the number of variables.关键词
专利生存期/中国/影响因素/生存分析Key words
determinants/ patent duration/ survival analysis/ China invented US patents分类
社会科学引用本文复制引用
任声策,尤建新..中国专利生存期:基于中国在美专利数据的实证[J].管理工程学报,2012,26(4):77-83,7.基金项目
国家自然科学青年基金资助项目(70902074) （70902074）
中国博士后科学基金资助项目(20090460656,201003278) （20090460656,201003278）
教育部人文社会科学研究一般项目资助(09YJC790185) （09YJC790185）
上海海事大学重点学科资助(XR0101) （XR0101）
