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Loet Leydesdorff

Publications and source records attributed to Loet Leydesdorff.

At least 145 records · Page 8Linked to original sources
arXiv2012

An Integrated Impact Indicator (I3): A New Definition of "Impact" with Policy Relevance

Allocation of research funding, as well as promotion and tenure decisions, are increasingly made using indicators and impact factors drawn from citations to published work. A debate among scientometricians about proper normalization of citation counts has resolved with the creation of an Integrated Impact Indicator (I3) that solves a number of problems found among previously used indicators. The I3 applies non-parametric statistics using percentiles, allowing highly-cited papers to be weighted more than less-cited ones. It further allows unbundling of venues (i.e., journals or databases) at the article level. Measures at the article level can be re-aggregated in terms of units of evaluation. At the venue level, the I3 creates a properly weighted alternative to the journal impact factor. I3 has the added advantage of enabling and quantifying classifications such as the six percentile rank classes used by the National Science Board's Science & Engineering Indicators.

cs.DL↗
arXiv2012

Citation impact of papers published from six prolific countries: A national comparison based on InCites data

Using the InCites tool of Thomson Reuters, this study compares normalized citation impact values calculated for China, Japan, France, Germany, United States, and the UK throughout the time period from 1981 to 2010. The citation impact values are normalized to four subject areas: natural sciences; engineering and technology; medical and health sciences; and agricultural sciences. The results show an increasing trend in citation impact values for France, the UK and especially for Germany across the last thirty years in all subject areas. The citation impact of papers from China is still at a relatively low level (mostly below the world average), but the country follows an increasing trend line. The USA exhibits a relatively stable pattern of high citation impact values across the years. With small impact differences between the publication years, the US trend is increasing in engineering and technology but decreasing in medical and health sciences as well as in agricultural sciences. Similar to the USA, Japan follows increasing as well as decreasing trends in different subject areas, but the variability across the years is small. In most of the years, papers from Japan perform below or approximately at the world average in each subject area.

cs.DL↗
arXiv2012

How journal rankings can suppress interdisciplinary research. A comparison between Innovation Studies and Business & Management

This study provides quantitative evidence on how the use of journal rankings can disadvantage interdisciplinary research in research evaluations. Using publication and citation data, it compares the degree of interdisciplinarity and the research performance of a number of Innovation Studies units with that of leading Business & Management schools in the UK. On the basis of various mappings and metrics, this study shows that: (i) Innovation Studies units are consistently more interdisciplinary in their research than Business & Management schools; (ii) the top journals in the Association of Business Schools' rankings span a less diverse set of disciplines than lower-ranked journals; (iii) this results in a more favourable assessment of the performance of Business & Management schools, which are more disciplinary-focused. This citation-based analysis challenges the journal ranking-based assessment. In short, the investigation illustrates how ostensibly 'excellence-based' journal rankings exhibit a systematic bias in favour of mono-disciplinary research. The paper concludes with a discussion of implications of these phenomena, in particular how the bias is likely to affect negatively the evaluation and associated financial resourcing of interdisciplinary research organisations, and may result in researchers becoming more compliant with disciplinary authority over time.

cs.DL↗
arXiv2012

Accounting for the Uncertainty in the Evaluation of Percentile Ranks

In a recent paper entitled "Inconsistencies of Recently Proposed Citation Impact Indicators and how to Avoid Them," Schreiber (2012, at arXiv:1202.3861) proposed (i) a method to assess tied ranks consistently and (ii) fractional attribution to percentile ranks in the case of relatively small samples (e.g., for n < 100). Schreiber's solution to the problem of how to handle tied ranks is convincing, in my opinion (cf. Pudovkin & Garfield, 2009). The fractional attribution, however, is computationally intensive and cannot be done manually for even moderately large batches of documents. Schreiber attributed scores fractionally to the six percentile rank classes used in the Science and Engineering Indicators of the U.S. National Science Board, and thus missed, in my opinion, the point that fractional attribution at the level of hundred percentiles-or equivalently quantiles as the continuous random variable-is only a linear, and therefore much less complex problem. Given the quantile-values, the non-linear attribution to the six classes or any other evaluation scheme is then a question of aggregation. A new routine based on these principles (including Schreiber's solution for tied ranks) is made available as software for the assessment of documents retrieved from the Web of Science (at http://www.leydesdorff.net/software/i3).

cs.DL↗
arXiv2012

An Evaluation of Impacts in "Nanoscience & nanotechnology:" Steps towards standards for citation analysis

One is inclined to conceptualize impact in terms of citations per publication, and thus as an average. However, citation distributions are skewed, and the average has the disadvantage that the number of publications is used in the denominator. Using hundred percentiles, one can integrate the normalized citation curve and develop an indicator that can be compared across document sets because percentile ranks are defined at the article level. I apply this indicator to the set of 58 journals in the ISI Subject Category of "Nanoscience & nanotechnology," and rank journals, countries, cities, and institutes using non-parametric statistics. The significance levels of results can thus be indicated. The results are first compared with the ISI-Impact Factors, but this Integrated Impact Indicator (I3) can be used with any set downloaded from the (Social) Science Citation Index. The software is made publicly available at the Internet. Visualization techniques are also specified for evaluation by positioning institutes on Google Map overlays.

cs.DL↗
arXiv2012

Bibliometric Perspectives on Medical Innovation using the Medical Subject Headings (MeSH) of PubMed

Multiple perspectives on the nonlinear processes of medical innovations can be distinguished and combined using the Medical Subject Headings (MeSH) of the Medline database. Focusing on three main branches-"diseases," "drugs and chemicals," and "techniques and equipment"-we use base maps and overlay techniques to investigate the translations and interactions and thus to gain a bibliometric perspective on the dynamics of medical innovations. To this end, we first analyze the Medline database, the MeSH index tree, and the various options for a static mapping from different perspectives and at different levels of aggregation. Following a specific innovation (RNA interference) over time, the notion of a trajectory which leaves a signature in the database is elaborated. Can the detailed index terms describing the dynamics of research be used to predict the diffusion dynamics of research results? Possibilities are specified for further integration between the Medline database, on the one hand, and the Science Citation Index and Scopus (containing citation information), on the other.

cs.DL↗
arXiv2012

Sociological and Communication-Theoretical Perspectives on the Commercialization of the Sciences

Both self-organization and organization are important for the further development of the sciences: the two dynamics condition and enable each other. Commercial and public considerations can interact and "interpenetrate" in historical organization; different codes of communication are then "recombined." However, self-organization in the symbolically generalized codes of communication can be expected to operate at the global level. The Triple Helix model allows for both a neo-institutional appreciation in terms of historical networks of university-industry-government relations and a neo-evolutionary interpretation in terms of three functions: (i) novelty production, (i) wealth generation, and (iii) political control. Using this model, one can appreciate both subdynamics. The mutual information in three dimensions enables us to measure the trade-off between organization and self-organization as a possible synergy. The question of optimization between commercial and public interests in the different sciences can thus be made empirical.

physics.soc-ph↗
arXiv2012

Mapping (USPTO) Patent Data using Overlays to Google Maps

A technique is developed using patent information available online (at the US Patent and Trademark Office) for the generation of Google Maps. The overlays indicate both the quantity and quality of patents at the city level. This information is relevant for research questions in technology analysis, innovation studies and evolutionary economics, as well as economic geography. The resulting maps can also be relevant for technological innovation policies and R&D management, because the US market can be considered the leading market for patenting and patent competition. In addition to the maps, the routines provide quantitative data about the patents for statistical analysis. The cities on the map are colored according to the results of significance tests. The overlays are explored for the Netherlands as a "national system of innovations," and further elaborated in two cases of emerging technologies: "RNA interference" and "nanotechnology."

cs.CY↗
arXiv2012

Alternatives to the Journal Impact Factor: I3 and the Top-10% (or Top-25%?) of the Most-Highly Cited Papers

Journal Impact Factors (IFs) can be considered historically as the first attempt to normalize citation distributions by using averages over two years. However, it has been recognized that citation distributions vary among fields of science and that one needs to normalize for this. Furthermore, the mean-or any central-tendency statistics-is not a good representation of the citation distribution because these distributions are skewed. Important steps have been taken to solve these two problems during the last few years. First, one can normalize at the article level using the citing audience as the reference set. Second, one can use non-parametric statistics for testing the significance of differences among ratings. A proportion of most-highly cited papers (the top-10% or top-quartile) on the basis of fractional counting of the citations may provide an alternative to the current IF. This indicator is intuitively simple, allows for statistical testing, and accords with the state of the art.

cs.DL↗
arXiv2012

Betweenness Centrality as a Driver of Preferential Attachment in the Evolution of Research Collaboration Networks

We analyze whether preferential attachment in scientific coauthorship networks is different for authors with different forms of centrality. Using a complete database for the scientific specialty of research about "steel structures," we show that betweenness centrality of an existing node is a significantly better predictor of preferential attachment by new entrants than degree or closeness centrality. During the growth of a network, preferential attachment shifts from (local) degree centrality to betweenness centrality as a global measure. An interpretation is that supervisors of PhD projects and postdocs broker between new entrants and the already existing network, and thus become focal to preferential attachment. Because of this mediation, scholarly networks can be expected to develop differently from networks which are predicated on preferential attachment to nodes with high degree centrality.

cs.SI↗
arXiv2012

The Knowledge-Based Economy and the Triple Helix Model

1. Introduction - the metaphor of a "knowledge-based economy"; 2. The Triple Helix as a model of the knowledge-based economy; 3. Knowledge as a social coordination mechanism; 4. Neo-evolutionary dynamics in a Triple Helix of coordination mechanism; 5. The operation of the knowledge base; 6. The restructuring of knowledge production in a KBE; 7. The KBE and the systems-of-innovation approach; 8. The KBE and neo-evolutionary theories of innovation; 8.1 The construction of the evolving unit; 8.2 User-producer relations in systems of innovation; 8.3 'Mode-2' and the production of scientific knowledge; 8.4 A Triple Helix model of innovations; 9. Empirical studies and simulations using the TH model; 10. The KBE and the measurement; 10.1 The communication of meaning and information; 10.2 The expectation of social structure; 10.3 Configurations in a knowledge-based economy

cs.OH↗
arXiv2012

World Shares of Publications of the USA, EU-27, and China Compared and Predicted using the New Interface of the Web-of-Science versus Scopus

The new interface of the Web of Science (of Thomson Reuters) enables users to retrieve sets larger than 100,000 documents in a single search. This makes it possible to compare publication trends for China, the USA, EU-27, and a number of smaller countries. China no longer grew exponentially during the 2000s, but linearly. Contrary to previous predictions on the basis of exponential growth or Scopus data, the cross-over of the lines for China and the USA is postponed to the next decade (after 2020) according to this data. These long extrapolations, however, should be used only as indicators and not as predictions. Along with the dynamics in the publication trends, one also has to take into account the dynamics of the databases used for the measurement.

cs.DL↗
arXiv2011

Percentile Ranks and the Integrated Impact Indicator (I3)

We tested Rousseau's (in press) recent proposal to define percentile classes in the case of the Integrated Impact Indicator (I3) so that the largest number in a set always belongs to the highest (100th) percentile rank class. In the case a set of nine uncited papers and one with citation, however, the uncited papers would all be placed in the 90th percentile rank. A lowly-cited document set would thus be advantaged when compared with a highly-cited one. Notwithstanding our reservations, we extended the program for computing I3 in Web-of-Science data (at http://www.leydesdorff.net/software/i3) with this option; the quantiles without a correction are now the default. As Rousseau mentions, excellence indicators (e.g., the top-10%) can be considered as special cases of I3: only two percentile rank classes are distinguished for the evaluation. Both excellence and impact indicators can be tested statistically using the z-test for independent proportions.

cs.CY↗
arXiv2011

Visualization and Analysis of Frames in Collections of Messages: Content Analysis and the Measurement of Meaning

A step-to-step introduction is provided on how to generate a semantic map from a collection of messages (full texts, paragraphs or statements) using freely available software and/or SPSS for the relevant statistics and the visualization. The techniques are discussed in the various theoretical contexts of (i) linguistics (e.g., Latent Semantic Analysis), (ii) sociocybernetics and social systems theory (e.g., the communication of meaning), and (iii) communication studies (e.g., framing and agenda-setting). We distinguish between the communication of information in the network space (social network analysis) and the communication of meaning in the vector space. The vector space can be considered a generated as an architecture by the network of relations in the network space; words are then not only related, but also positioned. These positions are expected rather than observed and therefore one can communicate meaning. Knowledge can be generated when these meanings can recursively be communicated and therefore also further codified.

cs.CL↗
arXiv2011

The new Excellence Indicator in the World Report of the SCImago Institutions Rankings 2011

The new excellence indicator in the World Report of the SCImago Institutions Rankings (SIR) makes it possible to test differences in the ranking in terms of statistical significance. For example, at the 17th position of these rankings, UCLA has an output of 37,994 papers with an excellence indicator of 28.9. Stanford University follows at the 19th position with 37,885 papers and 29.1 excellence, and z = - 0.607. The difference between these two institution thus is not statistically significant. We provide a calculator at http://www.leydesdorff.net/scimago11/scimago11.xls in which one can fill out this test for any two institutions and also for each institution on whether its score is significantly above or below expectation (assuming that 10% of the papers are for stochastic reasons in the top-10% set).

cs.DL↗
arXiv2011

Which cities' paper output and citation impact are above expectation in information science? Some improvements of our previous mapping approaches

Bornmann and Leydesdorff (in press) proposed methods based on Web-of-Science data to identify field-specific excellence in cities where highly-cited papers were published more frequently than can be expected. Top performers in output are cities in which authors are located who publish a number of highly-cited papers that is statistically significantly higher than can be expected for these cities. Using papers published between 1989 and 2009 in information science improvements to the methods of Bornmann and Leydesdorff (in press) are presented and an alternative mapping approach based on the indicator I3 is introduced here. The I3 indicator was introduced by Leydesdorff and Bornmann (in press).

cs.DL↗
arXiv2011

A Rejoinder on Energy versus Impact Indicators

Citation distributions are so skewed that using the mean or any other central tendency measure is ill-advised. Unlike G. Prathap's scalar measures (Energy, Exergy, and Entropy or EEE), the Integrated Impact Indicator (I3) is based on non-parametric statistics using the (100) percentiles of the distribution. Observed values can be tested against expected ones; impact can be qualified at the article level and then aggregated.

cs.DL↗