Patent Citations Analysis and Its Value in Research Evaluation： A Review and a New Approach to Map Technology-relevant Research

Purpose： First, to review the state-of-the-art in patent citation analysis, particularly characteristics of patent citations to scientific literature （scientific non-patent references, SNPRs）. Second, to present a novel mapping approach to identify technology-relevant research based on the papers cited by and referring to the SNPRs. Design/methodology/approach： In the review part we discuss the context of SNPRs such as the time lags between scientific achievements and inventions. Also patent-to-patent citation is addressed particularly because this type of patent citation analysis is a major element in the assessment of the economic value of patents. We also review the research on the role of universities and researchers in technological development, with important issues such as universities as sources of technological knowledge and inventor-author relations. We conclude the review part of this paper with an overview of recent research on mapping and network analysis of the science and technology interface and of technological progress in interaction with science. In the second part we apply new techniques for the direct visualization of the cited and citing relations of SNPRs, the mapping of the landscape around SNPRs by bibliographic coupling and co-citation analysis, and the mapping of the conceptual environment of SNPRs by keyword co-occurrence analysis. Findings： We discuss several properties of SNPRs. Only a small minority of publications covered by the Web of Science or Scopus are cited by patents, about 3%-4%. However, for publications based on university-industry collaboration the number of SNPRs is considerably higher, around 15%. The proposed mapping methodology based on a ＂second order SNPR approach＂ enables a better assessment of the technological relevance of research. Research limitations： The main limitation is that a more advanced merging of patent and publication data, in particular unification of author and inventor names, in still a necessity. Practical implications： The proposed mapping methodology enables the creation of a database of technology-relevant papers （TRPs）. In a bibliometric assessment the publications of research groups, research programs or institutes can be matched with the TRPs and thus the extent to which the work of groups, programs or institutes are relevant for technological development can be measured. Originality/value： The review part examines a wide range of findings in the research of patent citation analysis. The mapping approach to identify a broad range of technologyrelevant papers is novel and offers new opportunities in research evaluation practices.

Understanding more about non-patent references

Non-patent references(NPRs)play an important role in the interaction between science and technology.In this contribution,we compare the characteristics of NPRs traced from patents on"metabolic engineering"to those received by the 10%most-cited articles(cited in scientific publications and excluding NPRs)in the same field.We observe that there is a low rate of co-citing articles between the two groups,and many NPRs have a better citation performance than TOP 10%articles.Our results provide preliminary clues to discover new characteristics of NPRs and to better understand the interface between science and technology.