Vicente P. Guerrero-Bote

A new approach to the metric of journals’ scientific prestige: The SJR indicator

A size-independent indicator of journals’ scientific prestige, the SCImago Journal Rank (SJR) indicator, is proposed that ranks scholarly journals based on citation weighting schemes and eigenvector centrality. It is designed for use with complex and heterogeneous citation networks such as Scopus. Its computation method is described, and the results of its implementation on the Scopus 2007 dataset is compared with those of an ad hoc Journal Impact Factor, JIF(3y), both generally and within specific scientific areas. Both the SJR indicator and the JIF distributions were found to fit well to a logarithmic law. While the two metrics were strongly correlated, there were also major changes in rank. In addition, two general characteristics were observed. On the one hand, journals’ scientific influence or prestige as computed by the SJR indicator tended to be concentrated in fewer journals than the quantity of citation measured by JIF(3y). And on the other, the distance between the top-ranked journals and the rest tended to be greater in the SJR ranking than in that of the JIF(3y), while the separation between the middle and lower ranked journals tended to be smaller.

Order-based fitness functions for genetic algorithms applied to relevance feedback

Recently there have been appearing new applications of genetic algorithms to information retrieval, most of them specifically to relevance feedback. The evolution of the possible solutions are guided by fitness functions that are designed as measures of the goodness of the solutions. These functions are naturally the key to achieving a reasonable improvement, and which function is chosen most distinguishes one experiment from another. In previous work, we found that, among the functions implemented in the literature, the ones that yield the best results are those that take into account not only when documents are retrieved, but also the order in which they are retrieved. Here, we therefore evaluate the efficacy of a genetic algorithm with various order-based fitness functions for relevance feedback (some of them of our own design), and compare the results with the Ide dec-hi method, one of the best traditional methods.

Citation-based metrics are appropriate tools in journal assessment provided that they are accurate and used in an informed way

In a reply to Jerome K. Vanclay’s manuscript “Impact Factor: outdated artefact or stepping-stone to journal certification?” we discuss the value of journal metrics for the assessment of scientific-scholarly journals from a general bibliometric perspective, and from the point of view of creators of new journal metrics, journal editors and publishers. We conclude that citation-based indicators of journal performance are appropriate tools in journal assessment provided that they are accurate, and used with care and competence.

Genetic algorithms in relevance feedback: a second test and new contributions

The present work is the continuation of an earlier study which reviewed the literature on relevance feedback genetic techniques that follow the vector space model (the model that is most commonly used in this type of application), and implemented them so that they could be compared with each other as well as with one of the best traditional methods of relevance feedback--the Ide dec-hi method. We here carry out the comparisons on more test collections (Cranfield, CISI, Medline, and NPL), using the residual collection method for their evaluation as is recommended in this type of technique. We also add some fitness functions of our own design.

What lies behind the averages and significance of citation indicators in different disciplines

The limitations of citation-based indicators include a lack of coverage, no normalization with respect to the length of reference lists (with a potential bias in favour of reviews), and different citation habits. As a consequence, the distributions of the indicators are not comparable across different disciplines. Here we show that the most popular journal citation indicators used in quality assessment — the journal impact factors of Thomson Scientific and the scientific journal rankings of Scopus — are strongly correlated with the proportion of within-database references, and even more so with the number of within-database recent references per paper. No significant correlations were found with other bibliometric magnitudes. We anticipate that these results will be a starting point for more sophisticated indicator models that take this dependence into account, and for the design of strategies aimed at extending such bibliometric databases as Thomson Scientific’s Science Citation Index or Elsevier’s Scopus to improve their capacity to evaluate all sciences.

Citation increments between collaborating countries

International collaboration enhances citation impact. Collaborating with a country increments the citations received from it. But some collaborating countries provide greater increments in this sense than others, and likewise some countries receive greater increments from their partner countries than others. We observed a certain tendency for these increments to be lower in countries with greater impacts. Also, all the countries studied had higher Domestic Impacts as a result of collaborating, although this increment was less than that obtained from other countries. Finally, there were differences in the behaviour of the countries between the various scientific disciplines, with the effects being greatest in Social Sciences, followed by Engineering.

Visualization of scientific co-authorship in Spanish universities: from regionalization to internationalization

Purpose – The purpose of this paper is to visualize the inter‐university and international collaboration networks generated by Spanish universities based on the co‐authorship of scientific articles.Design/methodology/approach – The approach takes the form of formulation based on a bibliometric analysis of Spanish university production from 2000 to 2004 as contained in Web of Science databases, applying social network visualization techniques. The co‐authorship data used were extracted with the total counting method from a database containing 100,710 papers.Findings – Spanish inter‐university collaboration patterns appear to be influenced by both geographic proximity and administrative and political affiliation. Inter‐regional co‐authorship encompasses regional sub‐networks whose spatial scope conforms rather closely with Spanish geopolitical divisions. Papers involving international collaboration are written primarily with European Union and North and Latin American researchers. Greater visibility is atta...

Import-export of knowledge between scientific subject categories: The iceberg hypothesis

The capacity to attract citations from other disciplines — or knowledge export — has always been taken into account in evaluating the quality of scientific papers or journals. Some of the JCR’s (ISI’s Journal Citation Report) Subject Categories have a greater exporting character than others because they are less isolated. This influences the rank/JIF (ISI’s Journal Impact Factor) distribution of the category. While all the categories fit a negative power law fairly well, those with a greater External JIF give distributions with a more sharply defined peak and a longer tail — something like an iceberg. One also observes a major relationship between the rates of export and import of knowledge.

Co-word based thematic analysis of renewable energy (1990---2010)

This article describes an analysis of keywords which was aimed at revealing publication patterns in the field of renewable energy, including the temporal evolution of its different research lines over the last two decades. To this end, we first retrieved the records of the sample, then we processed the keywords to resolve their obvious problems of synonymy and to limit the study to those most used. The final results showed a clear increase in scientific production related to alternative energies, and a structure corresponding to five major clusters which, at a finer level of resolution, were decomposed into 22. We analyzed the structure of the clusters and their temporal evolution, paying particular attention to uncovering the bursty periods of the different lines of research.

Journal maps, interactive overlays, and the measurement of interdisciplinarity on the basis of Scopus data (1996–2012)

Using Scopus data, we construct a global map of science based on aggregated journal–journal citations from 1996–2012 (N of journals = 20,554). This base map enables users to overlay downloads from Scopus interactively. Using a single year (e.g., 2012), results can be compared with mappings based on the Journal Citation Reports at the Web of Science (N = 10,936). The Scopus maps are more detailed at both the local and global levels because of their greater coverage, including, for example, the arts and humanities. The base maps can be interactively overlaid with journal distributions in sets downloaded from Scopus, for example, for the purpose of portfolio analysis. Rao‐Stirling diversity can be used as a measure of interdisciplinarity in the sets under study. Maps at the global and the local level, however, can be very different because of the different levels of aggregation involved. Two journals, for example, can both belong to the humanities in the global map, but participate in different specialty structures locally. The base map and interactive tools are available online (with instructions) at http://www.leydesdorff.net/scopus_ovl.