Basic Journal Terminology_2016
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This document defines and explains several metrics used to measure the impact and quality of academic journals, including: 1. Impact factor, which measures the average number of citations to recent articles over a 2 year period. 2. 5-year impact factor, eigenfactor, article influence, SJR, and SNIP, which also measure citations but use different calculation methods. 3. Review speed and online publication time, which indicate how quickly journals process submissions and make articles available.
Basic Journal Terminology_2016
- 1. Page 0 of 5 Courtesy to Elsevier, 2016 Friday, August 26, 2016 Some basic terminology and definition of Journal items, like Impact factor, Eigen factor, etc. Basic Journal Terminology How to judge the impact of journals. Compiled By: Atiqa Ijaz Khan M.Phil. Geomatics
- 2. Friday, August 26, 2016 Courtesy to Elsevier, 2016 Page 1 of 5 IMPACT FACTOR DEFINITION Impact Factor The Journal Impact Factor is published each year by Thomson Reuters. It is a measure of the number of times an average paper in a particular journal is cited during the preceding two years. For example: A = the number of times articles published in a specific journal in 2009 and 2010 were cited by journals during 2011. B = the total number of 'citable items' published by that journal in 2009 and 2010. ('Citable items' are usually articles, reviews, proceedings, etc.; not editorials or letters-to-the-editor.) 2011 impact factor = A/B. Actual value is intentionally only displayed for the most recent year. Earlier values are available in the Journal Citation Reports from Thomson Reuters ISI ranking Journals are often ranked by Impact Factor in an appropriate Thomson Reuters subject category. As there are now two Impact Factors published – two-year and five-year Impact Factors – this rank may differ, so care is needed when assessing these ranked lists to understand which of the two metrics is being used. In addition, journals can be categorized in multiple subject categories, giving them different ranks for each subject. Consequently, a rank should always be in context to the subject category. 5 – YEAR IMPACT FACTOR DEFINITION Impact Factor A base of five years may be more appropriate for journals in certain fields because the body of citations may not be large enough to make reasonable comparisons, or it may take longer than two years to publish and distribute leading to a longer period before others cite the work.
- 3. Friday, August 26, 2016 Courtesy to Elsevier, 2016 Page 2 of 5 Actual value is intentionally only displayed for the most recent year. Earlier values are available in the Journal Citation Reports from Thomson Reuters. ISI ranking Journals are often ranked by Impact Factor in an appropriate Thomson Reuters subject category. As there are now two Impact Factors published – two-year and five-year Impact Factors – this rank may differ, so care is needed when assessing these ranked lists to understand which of the two metrics is being used. In addition, journals can be categorized in multiple subject categories, giving them different ranks for each subject. Consequently, a rank should always be in context to the subject category. Eigen Factor DEFINITION Article Influence Article Influence is calculated by dividing the Eigenfactor® score by the percentage of all articles recorded in the Journal Citation Reports that were published in a specific journal. The Article Influence score measures the average influence per article of the papers in a journal. As such, it is comparable to Thomson Scientific's widely used Impact Factor. Article Influence scores are normalized so that the mean article in the entire Thomson Journal Citation Reports (JCR) database has an article influence of 1.00. Eigenfactor® The Eigenfactor® score is a rating of the total importance of a specific journal. Journals are rated according to the number of incoming citations, with citations from highly ranked journals weighted to make a larger contribution to the Eigenfactor® than those from poorly ranked journals. As a measure of importance, the Eigenfactor® score scales with the total impact of a journal. Journals generating higher impact to the field tend to have larger Eigenfactor® scores. The Eigenfactor® approach is thought to be more robust than the Impact Factor metric, which counts purely incoming citations without considering the significance of those citations. Source-Normalized Impact per Paper (SNIP)
- 4. Friday, August 26, 2016 Courtesy to Elsevier, 2016 Page 3 of 5 DEFINITION SNIP/IPP Source-Normalized Impact per Paper (SNIP) measures contextual citation impact by weighting citations based on the total number of citations in a subject field. This unique perspective enables direct comparison of sources in different subject fields. The impact of a single citation is given higher value in subject areas where citations are less likely, and vice versa. It is a ratio, with a numerator and a denominator. SNIP's numerator is a journal's impact per publication (IPP). This is simply the average number of citations received in a particular year (e.g. 2013) by papers published in the journal during the three preceding years (e.g. 2010, 2011 and 2012). SNIP's denominator is the Database Citation Potential (DCP). We know that there are large differences between various scientific subfields in the frequency at which authors cite papers. In view of this, for each journal an indicator is calculated of the citation potential in the subject field it covers. This citation potential is included in SNIP's denominator, the DCP. SNIP is IPP divided by DCP. SNIP enables direct comparison of sources in different subject fields. Citation potential is shown to vary not only between journal subject categories (groupings of journals sharing a research field) or disciplines (e.g., journals in Mathematics tend to have lower values than journals in Life Sciences), but also between journals within the same subject category. For instance, basic journals tend to show higher citation potentials than applied or clinical journals. Likewise, journals covering emerging topics tend to be higher than periodicals in classical subjects, or more general journals. SNIP helps authors to identify which journals are performing best within their subject field, helping them decide where to publish. Mouse over the circles in the visualization and click on the year to view the journal's metrics. The size of the circles are compared to the highest values in the 5-year range. This highest value is represented by a closed circle, and the open circles indicate the journal's value compared to this highest value. SCImago Journal Rank (SJR)
- 5. Friday, August 26, 2016 Courtesy to Elsevier, 2016 Page 4 of 5 DEFINITION SJR SCImago Journal Rank (SJR) is a measure of the number of times an average paper in a particular journal is cited, 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 1.00 based on the rank of the citing journal. The weighting is calculated using a three-year window of measurement and uses the Scopus database. Authors can use these metrics when deciding where to publish. The idea is to assign weights to bibliographic citations based on the importance of the journals that issued them. Citations issued by more important journals will be more valuable than those issued by less important ones. This 'importance' will be computed recursively, i.e., the important journals will be those which in turn receive many citations from other important journals. REVIEW SEED DEFINITION Review Speed The average number of weeks it takes for an article to go through the review process for this journal. There are two key periods: 1. From manuscript submission to the initial decision on the article. 2. From manuscript submission to the final decision. When you mouse over the green and white circles in the graph above, the average number of weeks for an article in this journal to reach these key points is displayed. DEFINITION Online Article Publication Time The average number of weeks an article takes to reach key points in the online publication process. There are two key periods: 1. From manuscript acceptance to the first appearance of the article online (with DOI).
- 6. Friday, August 26, 2016 Courtesy to Elsevier, 2016 Page 5 of 5 2. From manuscript acceptance to the final appearance online of the fully paginated article. When you mouse over the green and white circles in the graph above, the average number of weeks for an article in this journal to reach each key point is displayed. AUTHORS DEFINITION Authors Our authors submit research articles from all over the world. Authors collaborate frequently with peers at different institutions and in different countries. This graph indicates the number of primary corresponding authors at the country level in the last five years.