H-index has been created with the purpose of measuring authors' productivity and influence, calculating the number of publications and the citations received.
If the author's H-index = 10, it means that he wrote 10 articles each cited 10 times.
Both databases as well as Google Scholar allow calculating the H-index. The calculation may vary depending on the database taken into account; therefore, it is always advisable to indicate the source.
Hc-index (contemporary H-index)
The contemporary H-index has been introduced to correct some limitations of the H-index, e.g. the penalization of younger scientists and of disciplinary areas reporting a lower number of citations.
The contemporary H-index is not provided by citational databases and it has to be calculated, using the same calculation of the H-index with the addition of the following corrective formula:
(4 x n. of document's citations) / (current year - document's publication year + 1)
The indicators reporting * were used for the VQR assessment exercises.
Impact Factor (IF)*
It measures the journal’s impact normalizing the raw number of citations dividing them by the number of published articles during the previous two (annual IF) or five years (five-years IF).
It measures the journal’s impact normalizing the raw number of citations dividing them by the number of published articles in the same year of publication of the article..
It indicates the number of articles used for the calculation of the Impact Factor. The typologies of the articles considered in the calculation are scientific papers and reviews only. Editorials, newsletters, and the like are excluded..
It analyses the number of citations received by a journal with reference to the year of publication of the Journal of Citation Report (current JCR). It is a metric that helps understanding how old the cited publications are, considering the average age of the articles cited in the JCR’s year of reference (e.g. a 2015 Cited Half-Life value of 7.0 for the Journal X indicates that half of the documents cited in the journal in 2015 have been published in the last 7 years)..
It undertakes the same kind of analysis showing the data from the citing journals perspective and verifying their average age (e.g. a Citing Half-Life value of 4.6 indicates that the average age of the citations is 4.6 years)..
It measures the impact of a journal using an algorithm similar to Page Rank, i.e. it calibrates the citations taking into account their sources. Citations from highly quoted journals have a higher score than those contained in less cited ones. The calculation groups the citations received in a specific year by the articles published in the previous five. It does not take into account self-quotations and the journal dimension..
Based on the value of the Eigenfactor (EF), it normalizes its result dividing the EF value by the number of articles published in the journal in the past 5 years..
Articles in citable items
It shows the percentage of citable articles making reference to the journal’s contents..
It is the normalized Eigenfactor score taking into account the total number of journals used in the calculation made by the JCR. This allows a comparison between journals and a measurement of their respective influence, making reference to an average one with relative score 1 (e.g. a journal with normalized Eigenfactor 5 is considered as five times more influential than the average journal in the JCR)..
Average JIF percentile
It indicates the average of the Journal Impact Factor as a percentage. The JCR percentile is the ranking of a journal in a specific disciplinary category expressed as a percentage..
It measures the impact of a journal calculating the average number of received citations in a calendar year by all the articles published in the same journal in the past three years. For instance, for the calculation of the Cite Score 2016, the citations received in 2016 are added to the articles published in 2013, 2014, and 2015, and divided by the number of articles published in that journal in the same time span..
Scimago Journal Rank (SJR)*
It measures the impact of a journal using an algorithm similar to Page Rank, taking into account the status of the citing journal as for Eigenfactor, yet considering the previous three years and a threshold for self-quotations..
Impact per Publication (IPP)*
It measures the impact of a journal as IF, yet making reference to a three-years’ time span (instead of two as for IF). It takes into account the same documentary typologies of IF, i.e. original papers and reviews. The values obtained are not normalized based on the disciplinary category..
Source Normalized Impact per Paper (SNIP)*
It measures the impact of a journal taking into account the coverage level of the journal’s disciplinary category, normalizing the IPP value with respect to the citing trend of the disciplinary category of the journal. The SNIP value is given by ratio of the received citations to the number of expected ones based on the size of the bibliographic references of the citing publications (citing potential). Therefore, it allows a comparison between journals categorized under different disciplinary fields..