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Using Journal Citation Reports

Compiled by Ilona Eberle and Robyn Tweedale

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What is covered:

What is indexed How the journal citation reports are calculated Impact factors and other measures JCR for Faculty staff and students

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What is indexed?

7500+ scholarly and technical journals from more than 3,300 publishers

It is the premier source of citation data on journals

It includes areas of science, technology, and social sciences

Journal Citation Reports can show you the:– Most frequently cited journals in a field– Highest impact journals in a field– Largest journals in a field

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What is indexed?

Journals used in:

– Science Citation Index– Social Sciences Citation Index

Traditional “Scholarly” journals

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What is NOT indexed?

Conference papers Grey literature Web or e-journals Australian journals (only 17 Social Science

and 63 Science Journals) New journals Anything outside the mainstream traditional

journal literature

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Journals can be viewed in a number of ways

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How the JCR are calculated

Number of articles published in a journal for a particular year

Number of citations to articles in that journal in previous years

Based on data from the previous two years (so each journal must be at least 3 years in the Citation Index to be included)

This is how the IMPACT FACTOR and other measures are calculated

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Journal Impact Factor

The journal impact factor is the average number of times articles from the journal published in the past two years have been cited in the JCR year

The impact factor is calculated by dividing the number of citations in the JCR year by the total number of articles published in the two previous years

– An impact factor of 1.0 means that, on average, the articles published one or two year ago have been cited one time

– An impact factor of 2.5 means that, on average, the articles published one or two year ago have been cited two and a half times

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For example…

NURSING RESEARCH

This gives a journal Impact factor of 1.604

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For example…

AMERICAN HISTORICAL REVIEW

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Other Measures Immediacy Index

– The immediacy index is the average number of times an article is cited in the year it is published

– The journal immediacy index indicates how quickly articles in a journal are cited

– The immediacy index is calculated by dividing the number of citations to articles published in a given year by the number of articles published in that year

NURSING RESEARCH:– Cites to 2006 articles in 2006 (15) / Articles published in 2006 (57) =

0.224 (Immediacy Index)

AMERICAN HISTORICAL REVIEW:– Cites to 2006 articles in 2006 (10) / Articles published in 2006 (22) =

0.224 (Immediacy Index)

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Other Measures Cited Half-life

– The median age of the articles that were cited in the JCR year

– Half of a journal's cited articles were published more recently than the cited half-life

– Only journals cited 100 or more times in the JCR year have a cited half-life

– A higher or lower cited half-life does not imply any particular value for a journal; it is subject-dependent, and also dependent on the rapidity of research change in that discipline

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Median???

The median is the exact centre number in a sequence…– So if articles were cited in these years

– Then the median year is 1998 and the median age is 6!

2004 2003 19931994199819992002 1992

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Other Measures Citing Half-life

– The citing half-life is the median age of articles cited by the journal in the JCR year

– Only journals that publish 100 or more cited references have a citing half-life

– For example, in JCR 2006, the journal Nursing Research has a citing half-life of 10.0 years - That means that 50% of all articles cited by articles in Nursing Research in 2006 were published between 1997 and 2006 (inclusive)

– In American Historical Review, the citing half-life is also 10 years, so more than 50% of all articles cited by articles in 2006 were published prior to 1997

– Again, this measure is very subject-dependent and based on the rapidity of change in research, so does not imply any particular value for a journal

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Journal Citing Half Life for American Historical Review

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Value of the Impact Factor

The impact factor mitigates the importance of absolute citation frequencies

It tends to discount the advantage of large journals over small journals because large journals produce a larger body of citable literature

For the same reason, it tends to discount the advantage of frequently issued journals over less frequently issued ones and of older journals over newer onesBecause the journal impact factor offsets the advantages of size and age, it is a valuable tool for journal evaluation

• Deciding on the key journals in a field or discipline

The impact factor trend graph shows the impact factor for a five-year period. To view the graph, click the Impact Factor Trend button at the top of the journal page

• Deciding on the increasing importance of a journal in a field or discipline

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Impact Factor Trend

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Immediacy Index

– Because it is a per-article average, the immediacy index tends to discount the advantage of large journals over small ones

– However, frequently issued journals may have an advantage because an article published early in the year has a better chance of being cited than one published later in the year

– Many publications that publish infrequently or late in the year have low immediacy indexes

– For comparing journals specializing in cutting-edge research, the immediacy index can provide a useful perspective

• Deciding on the key journals in a rapidly developing field or discipline

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Cited Half-life

– A primary research journal might have a longer cited half-life than a journal that provides rapid communication of current information

– Dramatic changes in cited half-life over time may indicate a change in a journal’s format.

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JCR in Collection Management

Citing Journal Graph– The Citing Journal graph shows the distribution trends of

articles in the selected journal, by cited year of citations

– All of the citing articles were published in the selected year (for example, 2004)

– So the distribution shown is for the articles in the 2004 issues of a journal, by cited year of the citations of those articles

– This information is useful in an individual analysis of a journal, in understanding its research depth and focus

• Analysing the research potential of a journal title

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Citing Journal Graph for American Historical Review

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JCR for Faculty staff

Staff will be interested primarily in the Impact Factor of a journal for:

Publishing decisions

Promotion rounds

Purchasing decisions and justifications

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JCR for Faculty

The usefulness of other measures, such as:

– Immediacy Index – if you are looking to publish in journals that get cited more quickly

– Cited Half-life – if you are researching in a rapidly-evolving field

– Citing Half-life – is another measure that reinforces a journal’s research depth for publishing and promotion