This letter documents some problems in Ancaiani et al. (2015). Namely the evaluation of concordance, based on Cohen's kappa, reported by Ancaiani et al. was not computed on the whole random sample of 9,199 articles, but on a subset of 7,597 articles. The kappas relative to the whole random sample were in the range 0.07-0.15, indicating an…

The literature on bibliometric indices for assessing scholarly impact, in particular the "h" index (Hirsch, 2005) and its many variants, is extensive, but nevertheless Ruscio and colleagues (this issue) succeed in making a valuable contribution. They have made the effort of collecting publication and citation data for no less than 1,750…

Ruscio and colleagues (Ruscio, Seaman, D'Oriano, Stremlo, & Mahalchik, this issue) have done a great service by systematically comparing indices of scholarly impact. Three aspects of their work are particularly valuable: (1) Their assessment of the proliferating collection of metrics, whose development has become something of a cottage industry,…

In their article Ruscio et al. (Ruscio, Seaman, D'Oriano, Stremlo, & Mahalchik, this issue) present a comparative study of some of the different variants of the "h" index. The study evaluates a total of 22 metrics, including the "h" index and "h"-type indices, as well as other conventional measures. The novelty of their work is to a large extent…

Describing, explaining, and discussing various modern indices of scholarly impact as accomplished by Ruscio, Seaman, D'Oriano, Stremlo, and Mahalchik (this issue) is highly commendable, as such measures get increasingly important in hiring and promotion decisions. The author agrees with almost all points made in the target article, except the…

Ruscio et al. (Ruscio, Seaman, D'Oriano, Stremlo, & Mahalchik, this issue) write of a thing with which scientists and scholars are all too familiar, the assessment of published research and of its authors. The author was startled to discover how little the agenda of the paper seems to engage with factors one relies on for salary and promotion…

Ruscio, Seaman, D'Oriano, Stremlo, and Mahalchik (this issue) evaluate 22 bibliometric indicators, including conventional measures, like the number of publications, the "h" index, and many "h" index variants. To assess the quality of the indicators, their well-justified criteria encompass conceptual, empirical, and practical…

This article presents the author's critique on "Measurement of Central Aspects of Scientific Research: Performance, Interdisciplinarity, Structure," by Anthony F. J. van Raan. It also presents a summary of recent work by the Leiden bibliometrics group, which van Raan has led so ably for more than 15 years. The group has established an excellent…

Bibliometrics has come of age and is generally accepted, together with peer review, as one way to describe the activity of players in science. Appealing issues in bibliometrics include the characterization of a growth regime of research systems including the trade-offs of production-visibility; the measure of science-technology linkage and…

Since the use of bibliometric instruments has grown and will continue to grow in the future, the quality, availability, and accessibility of data on publications and citations is of tantamount importance. But equally important is a correct use of the data. This means that an important task of the bibliometric field is to highlight not only what…

This article presents a rejoinder on the commentaries regarding the author's focus article titled, "Measurement of Central Aspects of Scientific Research: Performance, Interdisciplinarity, Structure," structuring comments around a number of main topics discussed by the authors of the commentaries. The author presents technical issues…

This article presents the author's critique of Anthony F. J. van Raan's article titled, "Measurement of Central Aspects of Scientific Research: Performance, Interdisciplinarity, Structure." van Raan makes an excellent case for using bibliometric data to measure some central aspects of scientific research and to construct indicators of…

This article presents the author's critique of "Measurement of Central Aspects of Scientific Research: Performance, Interdisciplinarity, Structure," by Anthony F. J. van Raan. The author states that van Raan's article provides an excellent, if tightly compressed, introduction to key findings and innovative methods of the accumulating and…