Patents cited in the scientific literature: An exploratory study of 'reverse' citation relations

This paper reports on a new approach to study the linkage between science and technology. Unlike most contributions to this area we do not trace citations of scientific literature in patents but explore citations of patents in scientific literature. Our analysis is based on papers recorded in the 1996-2000 annual volumes of the CD-Edition of Science Citation Index (SCI) of the Institute for Scientific Information (ISI) and patent data provided by the US Patent and Trademark Office. Almost 30,000 US patents were cited by scientific research papers. We analysed the citation links by scientific fields and technological sectors. Chemistry-related subfields tended to cite patents more than other scientific area. Among technological sectors, chemical clearly dominates followed by drugs and medical patents as the most frequently cited categories. Further analyses included a country-ranking based on inventor-addresses of the cited patents, a more detailed inspection of the ten most cited patents, and an analysis of class-field transfers. The paper concludes with the suggestions for future research. One of them is to compare our 'reverse' citation data with 'regular' patent citation data within the same classification system to see whether citations occur, irrespectively of their directionality, in the same fields of science and technology. Another question is as to how one should interpret reverse citation linkages.     

Bibliometric performance measures

Three different types of bibliometrics — literature bibliometrics, patent bibliometrics, and linkage bibliometric can all be used to address various government performance and results questions. Applications of these three bibliometric types will be described within the framework of Weinberg's internal and external criteria, whether the work being done is good science, efficiently and effectively done, and whether it is important science from a technological viewpoint. Within all bibliometrics the fundamental assumption is that the frequency with which a set of papers or patents is cited is a measure of the impact or influence of the set of papers. The literature bibliometric indicators are counts of publications and citations received in the scientific literature and various derived indicators including such phenomena as cross-sectoral citation, coauthorship and concentration within influential journals. One basic observation of literature bibliometrics, which carries over to patent bibliometrics, is that of highly skewed distributions — with a relatively small number of high-impact patents and papers, and large numbers of patents and papers of minimal impact. The key measure is whether an agency is producing or supporting highly cited papers and patents. The final set of data are in the area of linkage bibliometrics, looking at citations from patents to scientific papers. These are particularly relevant to the external criteria, in that it is quite obvious that institutions and supporting agencies whose papers are highly cited in patents are making measurable contributions to a nation's technological progress.     

Characterizing intellectual spaces between science and technology

The paper presents a methodology for studying the interactions between science and technology. Our approach rests mostly on patent citation and co-word analysis. In particular, this study aims to delineate intellectual spaces in thin-film technology in terms of science/technology interaction. The universe of thin-film patents can be viewed as the macro-level and starting point of our analysis. Applying a bottom-up approach, intellectual spaces at the micro-level are defined by tracing prominent concepts in publications, patents, and their citations of scientific literature. In another step, co-word analysis is used to generate meso-level topics and sub-topics. Overlapping structures and specificities that emerge are explored in the light of theoretical understanding of science-technology interactions. In particular, one can distinguish prominent concepts among patent citations that either co-occur in both thin-film publications and patents or reach out to one of the two sides. Future research may address the question to what extent one can interpret directionality into this.     

What is Special about Patent Citations? Differences between Scientific and Patent Citations

The emergence of pattent bibliometrics as a new branch of scientometrics necessitates a deeper understanding of the relationship between patents and papers. As this connection is established through the linkage between patents and research papers, one must have a clear idea of similarities and differences between patent and paper citations. This paper will investigate to what extent one can not only apply bibliometric methods to patents but also extend the existing interpretative framework for citations in research papers to the field of patent citations. After pointing out some parallels in the debates about the nature of citations in patents and scientific articles, the paper outlines those parts of bibliometric theory covering scientific citations that could be relevant to patent citations too. Then it highlights the specialties and peculiarities of patent citations. One major conclusion is that the general nature of a common framework for both scientific and patent citations would severely limit its usefulness, but research on academic citations might still be a great source of inspiration to the study of patent citations.     

Validation study: Patent citations as indicators of science and foreign dependence

The purpose of this study was to test whether the distribution of citations from issued U.S. patents could be used to measure the science dependence and the foreign dependence of patented technologies. The citations considered were front page references from U.S. patents citing to U.S. and foreign patents, to research papers and to other publications. Rankings based on the number of citations per patent to the scientific literature were compared to peer rankings of the science dependence of the technologies. Rankings based on the number of citations to foreign origin material, including foreign origin U.S. patents, foreign patents and foreign priority statements, were compared to peer rankings of the foreign dependence of the technological areas.For the analysis a total of 24 technologies were chosen. Twelve of these were judged in advance to be science dependent and twelve were judged in advance to be foreign dependent. A peer group of 19 high level R&D managers was asked to rank all 24 technologies in terms of both their science and their foreign dependence. The bibliometric rankings of the technologies, based on their citations, were then compared with the peer rankings of the technologies.Overall, a high degree of agreement was found between the experts' opinion as to the science and foreign dependence of the areas and the corresponding bibliometric rankings. For example, the eight technologies judged most science dependent by experts averaged 0.92 cites per patent to scientific journal papers, while the eight technologies judged least science dependent had only 0.05 references per patent to journal papers. Similarly, large and statistically significant differences were found in the number of cites to foreign origin material for the eight technologies judged most foreign dependent by the experts when compared with the eight technologies judged least foreign dependent by the experts. These findings provide support for the hypothesis that patent citation data can be used in technological indicators development, and in technological policy analysis. They imply that citation-based location and analysis of science and foreign dependent technologies is a valid research tool when applied to the U.S. patent system.     

Analysis of propensity to patent and science-dependence of large Japanese manufacturers of electrical machinery

Summary The paper aims to clarify the extent to which the results of scientific-oriented research conducted by corporations are reflected in their application-oriented research. Focusing on large Japanese manufacturers of electrical machinery, the paper analyses firm-level data on presentations of scientific papers that represent the results of scientific-oriented research activities, citations of scientific papers in patents, and inventions. The electrical machinery industry, a prototypical science-based industry, has been placing a growing emphasis on scientific-oriented research during the 1990's as is evident from trends in R&D expenses, scientific papers, and inventions. Regression analysis results suggest a complementary relationship between citations of basic scientific knowledge as presented in scientific papers on the one hand and acts of invention on the other hand, in the sense that a rise in citations corresponds to a rise in inventions. Moreover, the results suggest that invention efficiency (number of patent claims per unit of R&D expenditure) has been increasing during the 1990's. Furthermore, the results suggest that, given the exogenous influences on the patent system in Japan, it is necessary to include the number of patent claims when attempting to measure corporate technology development activity through the volume of patent applications. However, there was no finding of a clear relationship between the number of scientific papers and inventions. Implications of these results for corporate R&D strategy are examined.     

Patent-bibliometric analysis on the Chinese science — technology linkages

The purpose of this study is to explore the character and pattern of the linkage between science and technology in China, based on the database of United States Patent and Trademark Office (USPTO). The analysis is focused on the period 1995–2004, a rapid increasing period for Chinese US patents. Using the scientific non-patent references (NPRs) within patents, we investigate the science-technology connection in the context of Chinese regions as well as industrial sectors classified by International Patent Classification (IPC). 11 technological domains have been selected to describe the science intensity of the technology. The results suggest that the patents and the corresponding scientific citations are related in different ways. Finally, we match the scientific NPRs to the Science Citation Index (SCI) covered publications to identify the core journals and categories. It reveals that the scientific references covered by SCI show a skewed distribution not only in journals but also in categories.     

Significant difference of dependence upon scientific knowledge among different technologies

Summary The authors have constructed an original database of the full text of the Japanese Patent Gazette published since 1994. The database includes not only the front page but also the body text of more than 880,000 granted Japanese patents. By reading the full texts of all 1,500 patent samples, we found that some inventors cite many academic papers in addition to earlier patents in the body texts of their Japanese patents. Using manually extracted academic paper citations and patent citations as “right” answers, we fine-tuned a search algorithm that automatically retrieves cited scientific papers and patents from the entire texts of all the Japanese patents in the database. An academic paper citation in a patent text indicates that the inventor used scientific knowledge in the cited paper when he/she invented the idea codified in the citing patent. The degree of science linkage, as measured by the number of research papers cited in patent documents, is particularly strong in biotechnology. Among other types of technology, those related to photographic-sensitized material, cryptography, optical computing, and speech recognition also show strong science linkage. This suggests that the degree of dependence on scientific knowledge differs from technology to technology and therefore, different ways of university-industry collaboration are necessary for different technology fields.     

The citation impact of social sciences and humanities upon patentable technology

This paper examines the citation impact of papers published in scientific-scholarly journals upon patentable technology, as reflected in examiner- or inventor-given references in granted patents. It analyses data created by SCImago Research Group, linking PATSTAT’s scientific non-patent references (SNPRs) to source documents indexed in Scopus. The frequency of patent citations to journal papers is calculated per discipline, year, institutional sector, journal subject category, and for “top” journals. PATSTAT/Scopus-based statistics are compared to those derived from Web of Science/USPTO linkage. A detailed assessment is presented of the technological impact of research publications in social sciences and humanities (SSH). Several subject fields perform well in terms of the number of citations from patents, especially Library and Information Science, Language and Linguistics, Education, and Law, but many of the most cited journals find themselves in the interface between SSH and biomedical or natural sciences. Analyses of the titles of citing patents and cited papers are presented that shed light upon the cognitive content of patent citations. It is proposed to develop more advanced indicators of citation impact of papers upon patents, and ways to combine citation counts with citation content and context analysis.

     

Linkage between patents and papers: An interim EPO/US comparison

A unification of more than one million non-patent references (NPR's) on the front pages of U.S. and EPO patents has been carried out, with a subsequent match to theScience Citation Index (SCI), in order to investigate the citation linkage between patented technology and the scientific research literature. The U.S. system shows an extremely rapid increase in linkage, with citations from U.S. patents to U.S. authored papers increasing more than three-fold over the last decade. The EPO system does not show any increase; the occurrence of non-patent references appears to be relatively constant in the EPO system over the last decade. In the U.S. system approximately 75 percent of the cited papers originate in public science institutions, showing large dependence of patented industrial technology on public science. We expect to find similar result in the EPO system.     

Indicators and the relations between science and technology

The relationship between science and technology is an important issue, as science-based technologies play a key role in modern economies. The exploration of the science-technology interface can be effectively supported by quantitative indicators, in particular patents of scientific institutions, publications of industrial enterprises, and scientific references in patent search reports. The most promising approach is the parallel observation of patents and publications in order to analyse the dynamics of the interaction of science and technology and the professional move of academic and industrial researchers between institutions.     

The growing number of patent citations to scientific papers: Changes in the world,nations, and fields

This study analyzes USPTO patents in the period 1998–2017. The number of science-related patents has increased twice as fast as the number of patents and scientific publications, and the number of cited papers per patent has almost doubled. These results vary substantially from one scientific and technological field to another. The proportion of the research papers cited by a patent has doubled. It refers to papers that are mostly published by the countries that have developed both scientific and technological capability and, surprisingly, are mainly used by inventors abroad. However, a weak relationship between the number of citations received from patents and papers reveals that the assessment of research performance needs some changes as the percentage of papers related to the innovations has grown over time.     

Measuring impacts of academic science on industrial research: A citation-based approach

Summary This paper introduces a citation-based metholodology to characterize and measure the magnitude and intensity of knowledge flows and knowledge spillovers from the public research sector to basic and strategic research in the private sector. We present results derived from an interrelated series of statistical analyses based on Private-to-Public Citations (PrPuCs) within reference lists of the research articles produced by industrial researchers during the years 1996-2003. The first part of the results provides an overview of PrPuC statistics worldwide for OECD countries. Overall, 70% to 80% of those references within corporate research papers relate to papers produced by public research organizations. When controlling for the size of their public sector research bases, Switzerland and the United States appear to be the major suppliers of 'citable' scientific knowledge for industrial research - the value of their Corporate Citation Intensity (CCI) exceeds their statistically expected value by more than 25%. A country's CCI performance turns out to be closely related to the citation impact of the entire domestic science base. The second section deals with an exploratory case study devoted to Electrical Engineering and Telecommunications, one of the corporate sector's major research areas. The findings include a list of the major citing and cited sources at the level of countries and organizations, as well as an analysis of PrPuCs as a “missing link”connection intra-science citations and citations received from corporate science-based patents.     

The evidence of systematic noise in non-patent references: A study of New Zealand companies’ patents

Since the pioneering studies of Carpenter & Narin (1983), and Narin & Noma (1985), non-patent references (NPRs) in patent documents have been widely used as an indicator of science-technology links. Meyer (2000) reviewed previous work in the patent citation literature and found that citation links between patents and papers are, if not explicitly, at least implicitly viewed as an indication of the contribution of science to technology. Using a sample of 850 patents of New Zealand companies granted by the USPTO between 1976 and 2004, we find evidence of systematic noise in NPR data. We suggest that future research should pay close attention to heterogeneity among countries, and that one should demonstrate more caution in applying and interpreting results based on the NPR methodology.     

Large firms and the science-technology interface Patents,patent citations,and scientific output of multinational corporations in thin films

Firms operating in science-based technological fields reflect some of the complexities of the science-technology interaction. The present study attempts to investigate these interactions by analyzing patent citations, publication and patent outputs of multinational corporations (MNCs) in 'thin film' technology. In particular we explore different characteristics of knowledge production and knowledge utilization of these firms. The results indicate no correlation between intensity of research activity and patents produced by the MNCs. The relationship between scientific and technological knowledge generation as well as the linkage between science and technology appear to be firm-specific rather than dependent on a technological or industrial sector. The dispersion of journal sources for the majority of patent citations of scientific literature as well as for the majority of scientific outputs is narrow. Basic journals play an important role in patent citation as well as in addressing research of MNCs in thin-film technology.     

The public science base of US biotechnology: A citation-weighted approach

In previous research we examined the science base of US biotechnology utilizing several unique patent and scientific paper databases (McMillan et al., 2000). Our findings highlighted the importance of public science in this industry. In this current research effort, we extend that analysis to include the subsequent citations those biotechnology patents received. Our conclusions are that the reliance on public science is stable when adjusted for forward citations, but the impact of different funding sources does change when citation weights are added. The science policy implications of these findings and future research opportunities are discussed.     

Pharmacology and Pharmacy: research and innovation analysis

Pharmacology and Pharmacy has a highly vertiginous evolution at international level. Its results are widely applied in the pharmaceutical industry, which is in the first places internationally. The study is aimed to analyse the behaviour of the leading institutions at global level in terms of production of papers and patents; as well as the impact that these contributions generate. The databases used were Science Citation Index and Derwent Innovation Index, both belonging to Web of Science platform. The InCite tool was used to analyse the period from 2000 to 2019. It was demonstrated that there is no correspondence among the highlighted institutions in patent applications, patents granted and number of citations, as well as among entities with the highest number of papers, highly cited papers and number of citations. Leadership in the discipline of Pharmacology and Pharmacy is neither determined by their highly productive institutions nor the impact generated by them.

     

The highly cited papers of professors as an indicator of a research group's scientific performance

In the first part of the paper the citations in 1986 and 1987 of 3938 papers published in 1985 by 324 research groups in the faculties of science and of medicine of eight universities in the Netherlands are analyzed. Because of the large statistical spread of (1) the number of short-term citations of papers cited equally frequently over a long period, and (2) the number of citations over a long period of papers by the same author, short-term citation scores appear to be an unreliable indicator of a research group's contribution to science. In the second part of the paper an alternative approach is presented, based on a subdivision of the 3938 papers in papers authored by professors with 0–2, 3–8, or 9 highly cited papers (HCPs, 25 citations) to their name. Very large citation score differences were found for the three categories. For example: for papers first-authored by a professor, the average number of citations per person in 1986 and 1987 for 1985 papers was for 161 professors with 9 HCPs a factor 14 larger than for 575 professors with only 0–2 HCPs; for papers co-authored by professors, this factor was 6.6. These findings justify the conclusion that the number of HCPs scored by the professors (and other senior scientists) during their entire career is a much more reliable predictor of the performance of a research group than the number of short-term citations of the articles published by the group within a short period. A research group's contribution to science is primarily determined by the individual scientifictalents of its members.     

Can applied science be ‘good science’? Exploring the relationship between patent citations and citation impact in nanoscience

There is a rich literature on how science and technology are related to each other. Patent citation analysis is amongst the most frequently used to tool to track the strengths of links. In this paper we explore the relationship between patent citations and citation impact in nanoscience. Our observations indicate that patent-cited papers perform better in terms of standard bibliometric indicators than comparable publications that are not linked to technology in this way. More specifically, we found that articles cited in patents are more likely to be cited also by other papers. The share of highly cited papers is the most striking result. Instead of the average of 4% of all papers, 13.8% of the papers cited once or twice in patents fall into this category and even 23.5% of the papers more frequently cited in patents receive citation rates far above the standard. Our analyses further demonstrate the presence and the relevance of bandwagon effects driving the development of science and technology.