Page 127 - Academic and Research Book_WEB

Cited/Citing Half-Life

Although JIF provides an important tool in the hands of the librarians, they are always faced with
decisions about collection maintenance and de-acquisition of individual journals as well as how to
assess back file purchases for a journal. This is a very tricky issue and there are no easy solutions,
however, the metrics, Cited Half-Life and Citing Half-Life, throw some light on this issue. ‘Cited’
essentially implies citations received whereas ‘Citing’ implies citations given, both bring out the
journal’s importance for archival purposes also.
In the JCRs, chronological data are provided in the Citing and Cited journal packages, but not in a
form that lends itself to quick understanding of usage patterns. The Journal Half-Life Package presents
these data so that chronological patterns are easily discernible. The Half-Life for a journal can help
librarians decide how far back the collected issues in a journal’s catalogue should extend.
Cited Half-Life looks at the citations that the articles published earlier in the journal receives
(incoming citations) in the JCR data year. This metric helps us to understand the age of publications
that are currently getting cited. Journals can receive citations in one JCR data year to anything that
they have ever published, and the Cited Half-Life indicates how far back researchers go, when they
cite articles published in that particular journal. The Cited Half-Life is the median age of a journal’s
articles that were cited in the JCR data year. Half of a journal’s cited articles were published more
recently than the Cited Half-Life. For example, a 2015 Cited Half-Life of five years of a journal
implies that half of the journal papers that were cited in 2015 were published in the preceding five
years including the year 2015. It need not be a whole number, for example, four-and-a-half can as
well be the half-life. The half-life is always calculated from the latest year backwards. A citation’s
age is equal to the publication year of the citing item minus the publication year of the cited item.
This information can help one to assess back-file purchases for a journal. Cited Half-Life is a good
measure if one is interested in looking at a journal and finding out if older or newer material of the
journal is receiving attention.

Citing Half-Life looks at citations given by a journal in the JCR data year. It is specifically defined as
the median age of the citations produced by a journal during the JCR year. A citation’s age is equal to
the publication year of the citing item (i.e., JCR data year) minus the publication year of the cited item.
By definition, half of a journal’s outbound citations are to items published before the Citing Half-Life,
and half are to items published after the Citing Half-Life. If a journal has a Citing Half-Life of four, it
means the median age of citations given by it is four years—half of the citations are from items more
recent than four years, and the other half are older. Citing Half-Life gives a different perspective on
a journal’s relationship to its peers, for example, which journals it cites most and how far back that
citing relationship extends.

Newly Emerged Indicators : Eigenfactor, Article Influence, SNIP, SJR

To address some of the drawbacks of JIF and related metrics, and of CiteScore, efforts have been made
to develop new generation metrics, using both WoS and Scopus databases. These metrics involve
complex algorithm-based calculations involving network theory and other latest programming tools
for assessing the journals using the vast mesh of citations joining vast number of scholarly documents.
Essentially effort is made to include qualitative as well as quantitative aspects of citations to arrive
at performance indicators for the journals. Eigenfactor and Article Influence are based on WoS data,
whereas SNIP and SJR indicators are based on Scopus data.

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