In the past academics and researchers have had relatively few tools at hand for finding out which bits of their work are appreciated and used by other academics. There are well-known, first generation, proprietary citations tracking systems (like ISI Web of Science and Scopus) that cover only or chiefly well-established journals with long time-lags. In the digital-era there are also newer Internet-based systems drawing extensively on Google which now offer a much broader and more responsive picture of who is citing or using whom in academia. Both types of systems have pros and cons that we will discuss in detail, and we will give step-by-step guidance on how academics can use the systems to look at their own work.
Our best advice to researchers wanting to find out how their work is being used by other academics is to use a combination of the three best tools, which are:
- Harzing’s ‘Publish or Perish’ (HPoP) software, which is a tweaked version of Google Scholar that delivers rapid feedback and covers far more sources (and somewhat more diverse sources) than anything else;
- ISI Web of Science, which is most useful for senior academics with a slate of published work already in high impact journals, and for academics in the physical sciences; and
- Google Book Search and Google Scholar for people working in disciplines where books and other non-journal academic outputs are important.
In the main body of this chapter we review these three systems and quite a few alternatives in depth, and explain how they work, what each of them is good for, their limitations, and how to get the best possible results from each of them. Armed with our advice notes we suggest that readers try out these systems and see which ones seem to work best for their discipline and for tracking their particular type of research.
We begin with a small but key digression on how to maximise finding an academic’s name in a search engine so that her citations can be more easily tracked. Next we consider the older citation tracking systems that focus only on (some) journal articles. In section three we look at the new Internet-based systems.
If an academic has a distinctive author name (with an uncommon surname and plenty of initials to identify her uniquely) then it will easier to find out how many other authors are citing her research. However, if an author has an indistinct name (like Smith, Jones, Brown, Li, Dupont, etc. and only one initial), it will take longer to obtain the same accurate information. It may not be possible to efficiently use some of the best citation systems at all, such as Harzing’s Publish or Perish (HPoP), and an academic may have to piece together citations for each of their publications using the titles to exclude references to many namesakes. A key implication arise here for new researchers just starting out on academic career (or a mentor advising a new researcher). She must choose her author name with great care, using the full first name and adding her second name or initial if applicable. Academics should keep in mind that from now on (for the rest of their career) people will be looking for their work in a global-sized haystack of competing information.
In Britain and Europe generally there is a huge extra problem to citation tracking arising from the restrictive and old-fashioned practices of journal style sheets. Coming from mostly small countries it is still common to find that most European social science journals include only the first initials of authors in footnotes or reference lists, so that they do not give authors’ first names in full, nor include their second or subsequent initials. Since academic knowledge is now organised on a global scale this is very bad practice. In the US, where there are now over 300 million people, the demands of finding people in a larger society have generally meant that much better author details are included. This is a pattern that European academics and journal editors should urgently start to copy.
ISI completely ignores a vast majority of publications in the social sciences and humanities. Anne-Will Harzing (2010)
There are some well-established and proprietary systems for tracking citations, also known as bibliometric systems. Compiled by hand and run on mainframe computers, they started as far back as the 1970s, and the best-known now is the ISI Web of Knowledge (which has a Social Science Citation Index). Its main rival is the less well known Scopus. Since these mainframe systems went online they have become a lot more accessible and somewhat easier to use. Most academics, post-docs and PhD students should now be able to access one of them from their offices or home computers via their university library. (Few libraries will pay for both of them, because their subscriptions are expensive).
The companies that produce these systems (Thompson for ISI and Elsevier for Scopus) rightly stress that they are well-established and well-founded on decades of experience. The systems give accurate citation counts (without duplications or phantom citations) because they are human-edited systems – one reason why they are also expensive to produce and hence are charged for. Above all they emphasise that the carefully guarded portals of the ISI and Scopus only include academically verified journals and exclude irrelevant or non-standard sources. However, there are conflicts of interest in Scopus being run by a company that is itself a major global journal publisher. Both databases also have a strong vested interest in running their operations in a restrictive way, to protect their costly proprietary model.
University hierarchs and government research boards love the solid, IBM-era technology of these systems, and view their costliness as a sign of quality. In addition, there is a whole sub-community of scholars and consultants who have grown up to analyse scientific referencing, especially in the physical sciences. Practitioners in this sub-field of library science have invested a lot of intellectual capital in learning how to use these large systems. Because it requires years of apprenticeship to extract meaningful data from ISI and Scopus, most bibliometrics experts favour a strategy that presents their data as comprehensive of the best journals. This has hindered the development and recognition of newer internet-based systems and approaches.
Conventional citation systems like ISI and Scopus have some severe limitations that need to be kept in mind-especially by social scientists and academics in the humanities – because these systems cover only a limited number of journals, and no or few books. In addition, the indexing criteria for journals are lengthy and heavily weighted towards journals that have already accumulated a critical mass of citations from journals that are already in the index.
The two conventional systems have a heavy bias in coverage towards English-language and towards older established journals. ISI especially is heavily American- dominated. Because the US is a large and rich society, with many more academics in most social science fields than in Europe or any other region of the world, the conventional systems automatically tend to deliver rankings and statistics that are weighted heavily towards success in the US ‘market’, compared with the rest of the world. The ISI system does not cover references in books, (although it does cover some book reviews in journals). The Scopus System covers Book Series. Excluding books is a fairly small problem in the physical sciences, which explains why the ISI systems are set up in this way. But it is an insurmountably serious limitation across the humanities where books are the main mode of scholarly communication and a key vehicle of disciplinary development. The lack of book coverage poses is a serious difficulties for accurately measuring citations within ‘softer’ social science fields where books remain very important.
The older systems completely exclude references in working papers or conference papers, and hence have very long time lags. Publishing in a journal across the social sciences generally takes a minimum of two years from submission to publication, and often up to 3.5 years in the most competitive and technical fields like economics. In the interim, conference papers and working papers often provide many indications of how much work is being cited. But neither type of outputs is included in the ISI, nor in the Scopus index. Rather than reflecting the latest advances in academic research, these systems tend to reflect the output component of the discipline three or four years in the past. As a result of all these factors, ISI and Scopus only cover a low fraction of academic journal papers in social science published worldwide, and far less than the coverage in the physical sciences, which can be regarded as near complete.
Figure 2.1 assesses the effects of ISI’s limited coverage of social science research. It captures the internal coverage of the ISI databases in 2006 by showing the percentage of references made in ISI articles that were made to journal articles already included in the database.
Figure 2.1: How far the ISI Citation Indexes for 2006 include the references cited by articles contained in the database across groups of related disciplines
|Percentage of references cited in the ISI databaset hat are to other items included in the database|
|High (80-100%)||Medium (60-80%)||Low (40-60%)||Very low (less than 40%)|
|Molecular biology and biochemistry (90%)||Applied physics and chemistry||Mathematics (64%)||Languages and communication (32 to 40%)|
|Biological Sciences - humans (82 to 99%)||Biological sciences - animals and plants (c 75%)||Engineering (45 to 69%)||All other social sciences (24 to 36%)|
|Chemistry (88%)||Psychology and psychiatry (c.72%)||Computer sciences (43%)||Humanities and arts (11 to 27%)|
|Clinical medicine (85%)||Geosciences (62 to 74%)||Economics (43%)|
|Physics and astronomy (84 to 86%)||Social sciences in medicine (62%)|
Source: Centre for Science and Technology Studies, 2007, Tables 3.1 and 3.3.
If ISI is capturing as it claims the most important work in a field, then most of these references should be to articles elsewhere in the ISI database. Figure 3.1 shows that ISI’s internal coverage was indeed high in the medical and physical sciences, for instance over 90 per cent in physics. Across other STEM disciplines from four fifths to nearly all of the references are included. In more applied physical science fields this proportion falls to two thirds or three fifths, and in maths and engineering to between two and three fifths, a level that is relatively lower. Social sciences, however, are strongly affected by ISI’s coverage bias. With the exception of social sciences related to medicine, coverage for the rest of social sciences falls below 50%; for example, 43% for economics and between 24-36% for. The humanities are the most affected with only 11-27% of internal coverage. Most bibliometric experts acknowledge that the usefulness of these systems declines sharply if they include fewer than three quarters to two thirds of all journal articles world-wide.
In addition, how far does ISI’s strong orientation towards American journals affect coverage when we come to look at research undertaken in other countries, like the UK. A detailed analysis was undertaken of the research submitted to the UK’s Research Assessment Exercise for 2001 (covering publications in 1996-2000), providing a useful external measure of coverage. It found that the ISI database included five out of every six RAE items submitted in the physical sciences (the STEM disciplines) , but only one in four items for the social sciences, as Figure 2.2 demonstrates. These numbers are very similar to the ISI internal coverage numbers above, even though they relate to different dates. So the internal coverage estimates for the database as a whole and the UK-specific external estimates of coverage offer a similar picture.
Figure 2.2: The inclusiveness of the ISI database for items submitted to the UK’s Research Assessment Exercise of 2001
A final dimension to consider for the social sciences concerns the trends over time – has the ISI got better at including social science materials? Do its continuing problems perhaps reflect chiefly its origins in the physical sciences and initially rather restrictive approach to including journals? As the database has expanded along with the growth of social sciences journals and publishing, has it become any more inclusive? Figure 2.3 shows how the detailed ISI internal coverage of the social science disciplines changed over a decade and a half. There has indeed been a general substantial improvement in coverage of these disciplines, but one starting from a pretty low base. By contrast, in humanities subjects the ISI’s inclusiveness has generally either declined or increased only slightly. Subjects bridging from the social sciences into STEM disciplines also show increases in internal coverage, but with smaller percentage changes because they start from a higher initial base.
Figure 2.3: How far the ISI Citation Indexes have improved over time in their including the references cited by articles contained in the database across social science and neighbouring disciplines, from 1991 to 2006
|ISI's internal coverage (%) in||Percentage change 1991 to 2006|
|For comparison: Life sciences||93||87||7|
|Inter-disciplinary social sciences||40||33||21|
|Languages and linguistics||40||26||54|
|Information science, Communication science||32||32||0|
|History, Philosophy, Religion||27||24||13|
|Political science, Public administration||24||17||41|
|Creative arts, Culture, Music||14||17||-18|
Source: The data in the first three columns are from Centre for Science and Technology Studies, 2007, Table 3.3.
Notes: ‘Internal coverage’ means the percentage of references cited in articles in the ISI database that are to other items included in the database. The yellow-shaded rows here are those for social sciences, green for humanities, and blue for subjects that are primarily physical sciences or STEM subjects.
For many years the known deficiencies of the ISI databases in the social sciences were routinely acknowledged, but none the less were put somewhat on one side because the data represented one of the only sources of insight. However, in the modern era where there are viable alternatives (indeed superior options for most social scientists) this stance is no longer appropriate. Bibliometricians commissioned by the UK’s Higher Education Funding Council to help them consider the use of citations data recommended that it was not appropriate to rely on conventional citations systems like ISI unless the internal coverage of items approached four fifths (the ‘high’ level in Figure 3.1) (Centre for Science and Technology, 2007, pp.xx-xx). The lower that coverage gets in a field, the less useful ISI ratings could be for assessing scholarly performance. They recommended that in disciplines where less than 50 per cent of references are being included in ISI, citations analysis could not contribute reliable information to a research assessment process.
Bearing in mind ISI’s limited coverage and geographical bias, academics should interpret ISI citation data with some degree of caution. In the social sciences ISI does not in any sense provide a more accurate insight into the overall and global impacts of academic work than newer internet-based systems. It can offer, however, a somewhat better picture of academic impact for those disciplines which tend to focus on high-prestige American-based journal articles. As the US is still normally rated as the first or second most influential country in the world across all social science disciplines, this is an important consideration.
Box 2a explains how to access ISI and the somewhat complicated processes that are normally necessary to extract a record from it of how your work has been cited:
ISI can be a helpful system for expanding normal literature review searches. However, it doesn’t provide the very helpful ‘snippet-view’ materials that Google Scholar does, which can be very helpful in ascertaining what a paper is about if it has an obscure title, and which are more helpful for checking through the backlist works of particular authors. But ISI does provide a relatively useful means of checking for key terms in article titles. It has a good date record and hence is an effective way of surfacing some of the main journal articles with keywords in their titles in say the last 5 or 10 years, often the most relevant search periods.
Google has been the prime force in the development of article-finding, book-finding and citations-tracking systems free over the Internet, having ambitiously declared its mission to ‘to organise the world’s information.’ Less than a decade after its founding, the company’s twin academic research engines Google Scholar (for journal articles and other academic papers) and Google Books now dominate the university sector.
There are other similar internet-based systems. The nearest counterpart to Google Scholar is the little-known Scirus system from Elsevier, a free-to-use counterpart to their Scopus system which draws more widely on current working papers and conference papers. It operates similarly to Scholar and is worth checking as an additional source. In the US there are some other Scholar competitor sites, but they all rely on academics registering and voluntarily uploading materials. As many academics are unlikely to do this, the coverage of these sites (like CiteSeerX and getCITED) is now far too restricted and non-comprehensive to be very useful.
The current dominance of automatic search systems like Google Scholar (also an approach used by Scirus) derives from the fact that they voraciously and automatically record all citations. In particular they include:
- all ‘black’ literature in journal articles or books that has been definitively and formally published, plus
- less conventional ‘grey’ literature, such as working papers, conference papers, seminar discussions or teaching materials that has been issued in a less formal or definitive form – often, of course, including versions of material that is later formally published.
This inclusiveness makes Google Scholar far more up-to-date in its picture of academic debates and controversies in each discipline, especially so in fields like computer science and IT studies where the pace of change in technologies and social uses of IT is very rapid. Scholar also gives users much more immediate information about the work being found, and it often gives full-text access to it if the material is not in a published book or placed behind a journal pay wall.
The dominance of automatic systems has been strengthened (and the obsolescing of American voluntary article-aggregator sites has been speeded up) by the growth of online research depositories in most serious universities in the advanced industrial countries. These university archives now host copies of their professors’ and lecturers’ works that previously were accessible only with great difficulty (by going to each individual author’s personal website) or behind journal pay walls. University online depositories also often contain conference and working papers that have not yet been formally published in journals, which Scholar and Scirus can both access and provide immediate full text access to.
Another useful development for Scholar and Scirus has been the development of some important multi-institutional sources hosting key research in pre-journal forms for free download. In the physical sciences newsletters and research feeds now often sustain a vigorous window into professional culture and current developments. In the social sciences these networks are somewhat less developed, but research paper depositories are big news. Two of the most important are the multi-field Social Science Research Network (SSRN) and in American economics the National Bureau for Economic Research (NBER),. But there are many others.
For assessing citations in journal articles, papers and related materials, at first sight it seems clear that Scholar and Scirus should be the most useful search tools. However, there are also four significant problems.
1) Both the Scholar and Scirus systems clearly access a range of mainly academic sources, but unlike ISI and Scopus neither company provides any full specification of exactly which sources they use. Scholar clearly searches many conventional academic index systems, as well as journals’ and publishers’ websites, conference proceedings, university sites and depositories and other web-accessible materials in academic contexts. But Google provides almost no information on exactly how this is done. This non-disclosure creates a big problem for government or professional bodies, and feeds their resolution not to take what Google says on trust.
2) For commercial reasons Google and Scirus are both equally secretive about the algorithms that they use to sort and search, in particular to discount duplicate entries for the same material, and how they count the remaining citations (after duplicates are removed). This is a highly sensitive subject and adds another barrier. However, the companies also argue that only by keeping their algorithms secret can they effectively counter spam, which is a growing and huge problem. Clearly if the ranking of sites could be distorted by spammers, the usefulness of Scholar or alternatives would be completely devalued.
3) Critics argue that because Scholar and Scirus are automated systems they sweep up together lots of different academic sources, some major journal articles, key professional conferences or major university e-depositories, but others quite likely of questionable academic status and provenance. So citations become blurred and over-inclusive, with far more marked variations in the ‘academic value’ or ‘research’ status of different citations than occur within the walled gardens of the ISI database.
4) Another problem with these systems is that they cannot recognise duplicated outputs, for example, a paper that is available both on a standard journal website and on the author’s personal website. This has implications for accurately counting the number of outputs and citations.
These are indeed serious problems if the purpose of accessing Google Scholar (or Scirus) were to rank scholars’ standing or citations to their research comparatively, or if its rankings were used to allocate rewards like research support funding between departments or universities. However, we have chosen to focus on two distinct features of these systems:
- allowing individual academics and researchers, or teams and departments to track their own citations; and
- expanding literature searches of other authors’ or researchers’ main works.
For both purposes, these four key problems are still worth bearing in mind, but they are only limitations that emphasise the need for individual judgement by the person consulting them. Authors and research teams know their own work better than anyone else in the world, and are therefore better able to analyse the data.
In addition, there are now simplified and tweaked forms of accessing Google Scholar, of which the most important is the ‘Public or Perish’ software available for free download from www.harzing.com/pop.htm. This is a valuable programme that combats many of the problems of interpreting Google Scholar outputs and allows academics to easily check their own or others’ performance.. It presents academic outputs quickly and computes excellent citation statistics about each author’s work, including a overall ‘times cited’ score and times cited per year since publication. We will continue the discussion of the more complex versions of HPoP citation statistics in section 2.4. Box 2b explains how to download and use the programme.
Google Books is a system that is primarily designed to make available a range of different online views of a book’s contents to potential readers. Essentially Google has now run around 10 million books through optical character readers so as to create online images of each page. For books that are out of copyright, Google makes available the full text for reading online, but the material cannot be downloaded in the free use version of the programme. The text of most out of copyright books is also fully searchable, so you can easily find specific sentences, quotations, or words of interest anywhere in the book. This software is so powerful and so good that many scholars now use Google Books as an online index to find material within books that they already have on their shelves, but which have either no index or the normally very inadequate academic book index system. There are also links through from Google Books to the publisher’s website, to booksellers offering the book, or to libraries nearby to the searchers’ location that stock it.
For books in copyright how much information is viewable on Google Books depends on what agreement the book’s publisher has reached with them. The most restrictive ‘no preview’ entry just replicates the publishers’ blurb and perhaps gives the contents pages. The next most restrictive approach is a ‘snippet view’ that offers only a few short glimpses of the book’s content, but still allows readers to search the full text and to find relevant material. If you want to find out if a book covers the kind of topic you are interested in, even in snippet view you can very quickly check far more material in a fraction of the time that would be needed for previous literature searches. The most expansive Google Books preview allows you to read many full pages of the text, but normally will leave out some key chapters or sections. However, you can usually search across the omitted sections as well as the full text pages (helpful for knowing how much coverage a book gives to your topic of interest). But again you cannot download a copy of the book in the free version.
Eventually, Google Books will be available worldwide in a commercial version that will make all copyrighted books in its database available for download, of course in return for a fee that will be agreed between Google, the publishers and universities. Google will potentially have an enormous monopoly position here, in a market that is bound to grow very strongly in size and value over the next decade, as e-books take off. How governments in the US, Europe and other regions of the world decide to regulate Google’s operations of this key intermediary role will have very substantial consequences for how academic research develops, especially in the most book-based disciplines, such as the humanities and ‘softer’ social sciences.
Leaving these meta-issues on one side, however, what concerns us here is the citations-counting capacity of Google Books, and Box 2c explains how to use it.
It is worth comparing how the two broad categories of citations systems perform against each other. In general the HPoP/Google Scholar database is much more inclusive than the ISI one, especially in disciplines where books and book chapters are an important means of professional communication. Figure 2.4 shows how the ISI and HPoP indices compare. The top two parts show only the items included in the ISI, first on a linear scale (which shows a strong bunching of low-scoring items) and secondly on a logarithmic scale (which helps to spread out the lower scores and shows the patterns of data better). In every case the ISI cites score for a publication is less than the HPoP/Google Scholar score (the point where they would be equal being shown by the parity line).
Figure 2.4: The relationship between ISI and HPoP scores for one example academic, a senior professor in political science
Each blob represents one item’s citation scores
(a) Linear scales (coverage: ISI items only) (b) Log scales (coverage: ISI items only)
Notes: Figures 2.4a and b include only items in the ISI database for this academic; Figure 2.4c includes all items in the person’s HPoP listing with at least three cites. The HPoP scores have been manually cleaned to eliminate duplicate Google Scholar entries.
Figure 2.4c shows the scores for all the person’s HPoP scores. The items scoring high on HPoP but zero on the ISI are in all cases comprised of books, book chapters and journal articles in journals that are not indexed by ISI. Five of this author’s top 6 cited items fall into this category, and 12 of the person’s top 20 cited pieces.
Of course, a single example of this kind is only indicative, and so to get a broader picture we turn next to data from the Impacts Project Database (IPD) described in Annex 1: Impacts Project Database. Essentially we collated ISI and HPoP scores for all the traceable publications of a sample of 120 academics spread across five social science disciplines. We also carefully checked by hand all the publications listed in HPoP/Scholar and looked at all the sources citing them. We removed all duplicate entries, unacknowledged citations, publishers’ publicity materials etc to produce a completely ‘cleaned’ IPD score, one that also incorporated citations in books. We aggregated the ISI, HPoP and IPD scores for each academic concerned, and compared them.
Figure 2.5: The inter-relationship between ISI and HPoP scores, and between ISI and IPD scores, for 100 academics in the IPD
Each mark represents one author’s aggregate citation scores. Graphs are log scaled.
(c) Correlation coefficients between the aggregate scores for authors
|ISI scores||Harzing scores|
|Harzing scores||0.22 (0.24)|
|IPD scores||0.14 (0.46)||0.95** (0.0)|
Notes: Correlation coefficient (significance test, two-tailed).
Figure 2.5 shows a strong continuity with the picture drawn above. Most ISI cites scores for authors are much lower than their HPoP scores, although it is noticeable that one in 10 of the sample showed ISI scores that are higher than their HPoP score. One in twelve of the sample were rated by ISI as having a minimal score of 1, whereas their HPoP scores ranged from 0 to 2089 cites. (On a per author basis there are obviously fewer instances of ISI registering zero cites than was the case for the per item basis in Figures 2.4a, or (b) or (c).
Figure 2.5b shows that this picture is also strongly born out at the author level in the manually checked IPD scores. The key reason for this is shown in Figure 2.5c, where the HPoP/Scholar and IPD scores are shown to correlate almost perfectly (and of course significantly). By contrast, the ISI scores correlated weakly with the HPoP/Scholar scores for our sample, and even less well with the carefully checked IPD scores.
So far though these are rather aggregated analyses, at the level of an author’s whole profile of work. By pooling data across multiple authors, and looking instead at the level of individual items we can examine how the relationships between the ISI, HPoP and IPD scores operate at the level of individual publications. Figure 2.6 shows the results for all the publications of a small sub-sample of 15 academics taken from our 120 in the pilot survey. [We are in the process of extending the item level analysis to cover all authors in the pilot survey, so these early findings are indicative only at this stage – although the patterns here are so strongly marked that we do not expect them to change much on further analysis]. We essentially repeat here the previous analysis, but at the level of individual publications.
Figure 2.6: The relationship between ISI and HPoP scores, and between ISI and IPD scores, for all the publications of a subset of 15 academics drawn from the IPD
Each mark represents the citation scores for a single publication. Graphs are log scaled.
The previous patterns found are strengthened. Figures 2.6a and 2.6b show that only around a quarter of the score that individual social science publications get in the ISI database can be explained in terms of HPoP
/Google scholar citations, or in terms of the manually cleaned and checked IPD scores (also including manually checked Google Books scores). By contrast, Figure 2.6c shows that the HPoP/Google Scholar scores for all publications included in the analysis are very similar indeed to the checked IPD scores. Indeed the R squared proportion of variance explained is 97 per cent, meaning that the two indicators are clearly tapping the same phenomena. Interestingly, although our analysis eliminated a good deal of double counting in the HPoP/Google Scholar listings, none the less the checked IPD scores are somewhat above the parity line here – reflecting the role of Google Books in boosting item scores. The two indicators move closely in step, but are not exactly the same. By contrast, the ISI citations count for most social science publications is far less than the HPoP/Google Scholar or IPD counts.
The implications of this analysis are clear-cut for academics. The quickest, most reliable and most comprehensive way of understanding how their research is being cited is to run a HPoP/Scholar analysis of their outputs and to manually clean the results so as to correct for problems, as discussed above. The ISI cites scores perhaps add insight into which journal articles are being cited in other US-orientated research articles. But in most social science fields, and especially more book-orientated disciplines, the ISI simply does not include enough materials to be a useful or reliable guide to what is being found useful and cited by other members of the profession.