Impact of research

Author-level metrics, such as h-index, and journal-level metrics, such as Journal Impact Factor (JIF) or CiteScore, are just some of the quantitative indicators used in bibliometric analyzes.

Bibliometric indicators are based on citation analysis: the incidence of citations and practices in communicating the results differ depending on the communities and research topics, as well as being dependent on the temporal variable.

The impact assessment must therefore be carried out analytically and by comparing the values of a metric in the same disciplinary category and regarding the same time window.

All metrics have limitations, they should not be used as the only source of analysis or classification, but as support tools for qualitative evaluation (informed peer review, panel).

Journal-level metrics

The Journal Impact Factor is reported in the Journal of Citation Reports, calculated and searchable also through the citation database Web of Science, accessible under subscription.

To calculate the metric, 3 years of serial publication are required. Starting in 2021, JCR counts citations based on the early access of the final electronic version of an article (VoR), including them in the calculation of the JIF 2020.

CiteScore is a similar metric, calculated and provided by the Scopus citation database, accessible under subscription. CiteScore also includes “very recent” journals, with only one year of publication, with a variable window of 1-4 years.

Author-level metrics

The Hirsh-index or h-index is a metric referable to the single author (or groups of authors) and is represented and can be calculated in the author profiles both in Web of Science and in Scopus.

The two databases index sources that are not completely overlapping, both serial and monographic, are selected using editorial and qualitative criteria (WoS, Scopus), with different methodologies and timing: the calculation of the H-index may differ depending on the database consulted, as well as varying over time (it is good practice to quote the date and source of the calculation).

The article-level metrics CNCI (Category-Normalized Citation Impact) of InCites and FWCI (Field Weighted Citation Impact) in Scopus are easy to read: they both focus on the ratio of citations received, compared to the world average, forecast in the reference category. A value greater than 1 indicates that the predicted global mean has been exceeded.

Misleading metrics

Beware of fake metrics: when using bibliometric indicators in choosing the journal in which to publish, it is necessary to verify the actual calculation in the subscription citation databases. False metrics (or with names similar to the most well-known) are an indication of a journal or publisher is not credible.

Google Scholar does not provide for a selection of indexed content and does not offer information on the coverage of sources and the calculation of indicators. While Web of Science and Scopus are paid databases, Scholar is a free and freely accessible search engine on the web. It indexes specialized scientific and academic literature and has developed citation metrics that cover only research articles published since 2016.

Unique identifiers - Author IDs

Authors can work proactively to ensure that all their publications and citations are recognized and counted in the calculation of these indexes, by creating and using unique author identification profiles, such as ORCID or Publons. Authors may use the specific procedure in Scopus or Web of Science to report discrepancies, missing or incorrect attributions in their profiles or research products.

Normalized or "weighted" metrics, quartiles and percentiles

There are also synthetic "weighted" indicators (weighted metrics) depending on the disciplinary category or normalized by period, which allows a wider quantitative comparison between articles, journals or authors belonging to different disciplines or with different academic ages.

SNIP (Source Normalized Impact for Papers) and FWCI (Field Weighted Citation Impact) are two metrics of this type (respectively journal-level and article-level) present in Scopus, suitable for comparison between disciplines. The Journal Citation Indicator (JCI) also provides, in JCR and Web of Science, easy-to-interpret journal-level metrics, as is the CNCI article-level metric available in InCites.

The use of quartiles and percentiles of unweighted metrics (JIF Quartile, Average JIF Percentile, CiteScore Percentile ...), transforms the position in the category given by an absolute value into a quartile/percentile value, allowing a more meaningful comparison between categories. In InCites, it is possible to carry out easy comparisons between journals (and not only) using different normalized metrics.

Other metrics and qualitative indexing

Other approaches, such as altmetrics, analyzing activity in academic networks or open science-related metrics, play different roles in assessing the impact of academic and scientific output, without using bibliographic citation as a computational value.

For example, in the Master Journal List (free access through registration or subscription by the University) all the journals indexed in Web of Science are listed: for each journal, quantitative (JIF and other metrics) and qualitative information is available, with regards to the peer review carried out by the journal or to composite indicators such as the Transparency and Openness Promotion Guidelines (TOP) Factor.

ERIH PLUS is an index of academic journals for HSS (Humanities and Social Sciences), in which in addition to qualitative and editorial information, there is also news on the possible status of open access and on the compliance of the journal with the requirements set by the funders who adhere to PlanS.

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