Sunday, September 19, 2010

More on the THE Citations Indicator

See this comment on a previous post:


As you can see from the following paragraph(http://www.timeshighereducation.co.uk/world-university-rankings/2010-2011/analysis-methodology.html) Thomson has normalised citations against each of their 251 subject categories (it's extremely difficult to get this data directly from WOS).. They have great experience in this kind of analysis.. to get an idea, check their in-cites website http://sciencewatch.com/about/met/thresholds/#tab3 where they have citations thresholds for the last 10 years against broad fields.

Paragraph mentioned above:
"Citation impact: it's all relative
Citations are widely recognised as a strong indicator of the significance and relevance — that is, the impact — of a piece of research.
However, citation data must be used with care as citation rates can vary between subjects and time periods.
For example, papers in the life sciences tend to be cited more frequently than those published in the social sciences.
The rankings this year use normalised citation impact, where the citations to each paper are compared with the average number of citations received by all papers published in the same field and year. So a paper with a relative citation impact of 2.0 is cited twice as frequently as the average for similar papers.
The data were extracted from the Thomson Reuters resource known as Web of Science, the largest and most comprehensive database of research citations available.
Its authoritative and multidisciplinary content covers more than 11,600 of the highest-impact journals worldwide. The benchmarking exercise is carried out on an exact level across 251 subject areas for each year in the period 2004 to 2008.
For institutions that produce few papers, the relative citation impact may be significantly influenced by one or two highly cited papers and therefore it does not accurately reflect their typical performance. However, institutions publishing fewer than 50 papers a year have been excluded from the rankings.
There are occasions where a groundbreaking academic paper is so influential as to drive the citation counts to extreme levels — receiving thousands of citations. An institution that contributes to one of these papers will receive a significant and noticeable boost to its citation impact, and this reflects such institutions' contribution to globally significant research projects."


The quotation is from the bottom of the methodology page. It is easy to miss since it is separate from the general discussion of the citations indicator.

I will comment on Simon Pratt's claim that "An institution that contributes to one of these papers will receive a significant and noticeable boost to its citation impact, and this reflects such institutions' contribution to globally significant research projects."

First, were self-citations included in the analysis?

Second, do institutions receive the same credit for contributing to a research project by providing one out of twenty co-authors that they would for contributing all of them.

Third, since citation scores vary from one subject field to another, a paper will get a higher impact score if it is classified as a subject that typically receives few citations than as one in which citations are plentiful.

Fourth, the obvious problem that undermines the entire indicator is that the impact scores are divided by the total number of papers. A groundbreaking paper with thousands of citations would would make little difference to Harvard. Change the affiliation to a small college somewhere and it would stand out (providing the college could reach 50 papers a year)>

This explains something rather odd about the data for Alexandria University. Mohamed El Naschie has published many papers with several different affiliations. Yet the many citations to these papers produced a dramatic effect only for Alexandria. This, it seems, was because his Alexandria papers had a big effect because the total number of papers was so low.

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