Impact per Publication
The Impact per Publication (IPP) measures the ratio of citations in a year (Y) to scholarly papers published in the three previous years (Y-1, Y-2, Y-3) divided by the number of scholarly papers published in those same years (Y-1, Y-2, Y-3). The IPP metric uses a citation window of three years which is considered to be the optimal time period to accurately measure citations in most subject fields. Taking into account the same peer-reviewed scholarly papers in both the numerator and denominator of the equation provides a fair impact measurement of the journal and diminishes the chance of manipulation.
The IPP is comparable to the Impact Factor, but uses a citation window of three years (as opposed to two years for the Impact Factor) and uses peer-reviewed document types only (articles, conference papers and review papers) in the calculation of the metric (as opposed to using citations to all documents in the nominator and the number of "citable" documents only in the denominator for the Impact Factor). Also, Scopus' much broader coverage means that IPP is available for many more journals than the Impact Factor.
The IPP is not normalized for the subject field and therefore gives a raw indication of the average number of citation a publication published in the journal will likely receive. When normalized for the citation rate in the subject field, the raw Impact per Publication becomes the Source Normalized Impact per Paper (SNIP). Note that in the context of the calculation of SNIP, the raw Impact per Publication is usually referred to as RIP. Like SNIP, the raw Impact per Publication metric was also developed by Leiden University's Centre for Science & Technology Studies (CWTS). See detailed methodology.
Source Normalized Impact per Paper
An indicator called SNIP (Source Normalized Impact per Paper) was developed by Henk Moed who was then part of the CWTS bibliometrics group at the University of Leiden. The pre-calculated metric was added to the Scopus Journal Analyzer in early 2010 and is freely available at www.journalmetrics.com.
SNIP is a novel approach and as such provides a novel bibliometric perspective. The key idea behind SNIP is that it corrects for subject-specific characteristics of the field someone is publishing in. This means that, contrary to the Impact Factor, SNIP numbers can be compared for any two journals, regardless of the field they are in.
Additional points include:
Freely available on the web.
Calculated for more journals than the Impact Factor.
SNIP is defined as the ratio of the raw Impact per Publicatiopn divided by the Relative Database Citation Potential. The raw Impact per Publication is the same as IPP described above: the ratio of citations in year X to peer-reviewed papers published in years X-1, X-2 and X-3 divided by the number of peer-reviewed papers published in years X-1, X-2 and X-3. As such it is conceptually similar to the Impact Factor. For example, the 2010 SNIP is calculated by dividing citations made in 2010 to peer-reviewed papers published in 2007, 2008 and 2009, by the number of peer-reviewed papers published in 2007, 2008 and 2009. The resulting ratio is then divided by the Relative Database Citation Potential. See detailed methodology.
SCImago Journal Rank
The SCImago Journal Rank (SJR) was developed by SCImago, a research group from the University of Granada, Extremadura, Carlos III (Madrid) and Alcalá de Henares, dedicated to information analysis, representation and retrieval by means of visualization techniques.
SCImago Journal Rank is based on citation data of the more than 20,000 peer-reviewed journals indexed by Scopus from 1996 onwards, and is freely available at www.journalmetrics.com.
The central idea of SJR is that citations are weighted, depending on the rank of the citing journal. A citation coming from an important journal will count as more than one citation, a citation coming from a less important journal will count as less than one citation.
The SCImago Journal Rank of journal J in year X is the number of weighted citations received by J in X to any item published in J in (X-1), (X-2) or (X-3), divided by the total number of articles and reviews published in (X-1), (X-2) or (X-3).
SCImago Journal Rank is a measure of the number of times an average paper in a particular journal is referred to, and as such is conceptually similar to the Impact Factor. A major difference is that instead of each citation being counted as one, as with the Impact Factor, the SCImago Journal Rank assigns each citation a value greater or less than one based on the rank of the citing journal. The weighting is calculated iteratively from an arbitrary constant using a three-year window of measurement. See detailed methodology.
Additional information on SJR and a data file containing all SJR values can be found at www.journalmetrics.com.
h-index
The h-index was proposed in 2005 by Professor Jorge Hirsch, as a metric for evaluating individual scientists; the paper is freely available.
The h-index rates a scientist's performance based on his or her career publications, as measured by the lifetime number of citations each article receives. The measurement is dependent on both quantity (number of publications) and quality (number of citations) of an academic's publications.
If you list all of a scientist's publications in descending order of the number of citations received to date, their h-index is the highest number of their articles, h, that have each received at least h citations. So, their h-index is 10 if 10 articles have each received at least 10 citations; their h-index is 81 if 81 articles have each received at least 81 citations. Their h-index is one if all of their articles have each received one citation, but also if only one of all their articles has received any citations.
However, the h-index can be applied to any group of articles, including those published in a particular journal in any given year.
In the fictitious example below, the 80 articles published in a journal in a given year have been ranked by lifetime citations. The h-index of this journal for this year's content is 22, since 22 articles have each received at least 22 citations
Best Wishes:
Dr.Ehab Aboueladab - Email:ehab10f@gmail.com
