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Munich, Germany

Today, it is not clear how the impact of research on other areas of society than science should be measured. While peer review and bibliometrics have become standard methods for measuring the impact of research in science, there is not yet an accepted framework within which to measure societal impact. Alternative metrics (called altmetrics to distinguish them from bibliometrics) are considered an interesting option for assessing the societal impact of research, as they offer new ways to measure (public) engagement with research output. Altmetrics is a term to describe web-based metrics for the impact of publications and other scholarly material by using data from social media platforms (e.g. Twitter or Mendeley). This overview of studies explores the potential of altmetrics for measuring societal impact. It deals with the definition and classification of altmetrics. Furthermore, their benefits and disadvantages for measuring impact are discussed. © 2014 Elsevier Ltd. Source

Evaluative bibliometrics is concerned with comparing research units by using statistical procedures. According to Williams (2012) an empirical study should be concerned with the substantive and practical significance of the findings as well as the sign and statistical significance of effects. In this study we will explain what adjusted predictions and marginal effects are and how useful they are for institutional evaluative bibliometrics. As an illustration, we will calculate a regression model using publications (and citation data) produced by four universities in German-speaking countries from 1980 to 2010. We will show how these predictions and effects can be estimated and plotted, and how this makes it far easier to get a practical feel for the substantive meaning of results in evaluative bibliometric studies. An added benefit of this approach is that it makes it far easier to explain results obtained via sophisticated statistical techniques to a broader and sometimes non-technical audience. We will focus particularly on Average Adjusted Predictions (AAPs), Average Marginal Effects (AMEs), Adjusted Predictions at Representative Values (APRVs) and Marginal Effects at Representative Values (MERVs). © 2013 Elsevier Ltd. Source

Bornmann L.,Max Planck Innovation | Leydesdorff L.,University of Amsterdam
Journal of Informetrics | Year: 2013

The data of F1000 and InCites provide us with the unique opportunity to investigate the relationship between peers' ratings and bibliometric metrics on a broad and comprehensive data set with high-quality ratings. F1000 is a post-publication peer review system of the biomedical literature. The comparison of metrics with peer evaluation has been widely acknowledged as a way of validating metrics. Based on the seven indicators offered by InCites, we analyzed the validity of raw citation counts (Times Cited, 2nd Generation Citations, and 2nd Generation Citations per Citing Document), normalized indicators (Journal Actual/Expected Citations, Category Actual/Expected Citations, and Percentile in Subject Area), and a journal based indicator (Journal Impact Factor). The data set consists of 125 papers published in 2008 and belonging to the subject category cell biology or immunology. As the results show, Percentile in Subject Area achieves the highest correlation with F1000 ratings; we can assert that for further three other indicators (Times Cited, 2nd Generation Citations, and Category Actual/Expected Citations) the "true" correlation with the ratings reaches at least a medium effect size. © 2012 Elsevier Ltd. Source

Bornmann L.,Max Planck Innovation | Marx W.,Max Planck Institute for Solid State Research
Journal of Informetrics | Year: 2013

A proposal is made in this paper for a broadening of perspective in evaluative bibliometrics by complementing the (standard) times cited with a cited reference analysis for a field-specific citation impact measurement. The times cited approach counts the citations of a given publication set. In contrast, we change the perspective and start by selecting all papers dealing with a specific research topic or field (the example in this study is research on Aspirin). Then we extract all cited references from the papers of this field-specific publication set and analyse which papers, scientists, and journals have been cited most often. In this study, we use the Chemical Abstracts registry number to select the publications for a specific field. However, the cited reference approach can be used with any other field classification system proposed up to now. © 2012. Source

Bornmann L.,Max Planck Innovation
Journal of Informetrics | Year: 2013

Bibliometrics has become an indispensable tool in the evaluation of institutions (in the natural and life sciences). An evaluation report without bibliometric data has become a rarity. However, evaluations are often required to measure the citation impact of publications in very recent years in particular. As a citation analysis is only meaningful for publications for which a citation window of at least three years is guaranteed, very recent years cannot (should not) be included in the analysis. This study presents various options for dealing with this problem in statistical analysis. The publications from two universities from 2000 to 2011 are used as a sample dataset (n= 2652, univ 1= 1484 and univ 2= 1168). One option is to show the citation impact data (percentiles) in a graphic and to use a line for percentiles regressed on 'distant' publication years (with confidence interval) showing the trend for the 'very recent' publication years. Another way of dealing with the problem is to work with the concept of samples and populations. The third option (very related to the second) is the application of the counterfactual concept of causality. © 2013 Elsevier Ltd. Source

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