Is there an alphabetical bias in citations?

March 11, 2010

In Economics, there is a tradition to list multiple authors in alphabetical order, unless exceptional circumstances call for a different order. This implies that “alphaberically challenged” authors like me often get forgotten, either because they disappear in “et al.” or because they become also-rans. RePEc manages to correct for “et al.” in citations, but it is possible that because later co-authors get less name recognitions, they also get less cited when sole authors. Using data from authors registered in RePEc, here is are some simple statistics that could shed some light, or raise some new questions.

I split the over 23,000 author into 26 bins, one for each letter of the alphabet corresponding to the initial of their last name. First, see how the average number of distinct works authors have written for each of those bins. The graph below runs from A on the left to Z on the right. While this is not a straight line, it does not appear to be obviously trending up or down. The correlation is -0.27.

Distinct works per author, by author's initial A-Z

Now look at the number of citations per author. This time, if you blink a little, you can see a little downwards trend. The correlation is -0.45 and note also that the spread is much larger.

Citations per author, by author's initial A-Z

Now try again with citations per work. A downward trend is now more visible, and the correlation is -0.53, with a different of about one citation between start and end of alphabet. Note that these are just simple averages, without any control for anything else that could correlate with the alphabet and lead to lower citation counts. But it is not obvious what such a control could be. Conclusion? Is there a bias in citations against alphabetically challenged authors? Possibly, but it is not a large one.

Citations per work, by author's initial A-Z

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Posted by Christian Zimmermann

RePEc in February 2010

March 3, 2010

The big news this month is that we reached half a million journal articles indexed on RePEc. We counted 816,240 file downloads and 2,781,710 abstract views, statistics that now include data from EconomistsOnline. Also, the NEP service had a record number of downloads by subscribers.

We also got 13 new RePEc archives: Università Bocconi (III), Technical University Darmstadt (II), London School of Economics (III), Trinity College, American Economist, Universidades Públicas de Andalucía, Economic Research South Africa, University of Cape Town (II), Review of Finance and Banking, Einaudi Institute for Economic and Finance, Romanian Society for Economic Science, Bruegel and Université de Neuchâtel.

Finally, in terms of threasholds passed, we can report:

500,000 indexed articles
160,000 working papers with references
30,000 registered people
6,000 indexed books

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Posted by Christian Zimmermann

500,000 journal articles listed on RePEc

February 25, 2010

The number of articles indexed on RePEc has recently surpassed half a million, with 88% linked to an online version. All these articles have been published in over 1000 journals listed on RePEc.

Journal articles now comprise the majority of the research material on RePEc, but this has not always been so. In fact, in the early days of RePEc, working papers (pre-prints) constituted the vast majority. But as commercial publishers started noticing how popular RePEc and its services were becoming, they wanted to be listed as well. They made the effort of converting their meta-data to our format and make it available at no charge. A few years back, this would have been unimaginable. Little by little, all major publishers opened RePEc archives. Nowadays, it is small independent publishers who join, along with various open access journals that look for free and efficient dissemination of their content through RePEc.

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Posted by Christian Zimmermann

About author rights

February 17, 2010

Authors are always very happy when their paper is accepted for publication in a journal, as this shows that their work was deemed important but editors and referees. But they also want to make sure that their work gets read and does not disappear behind a subscription wall. There are several steps an author can take here.

Retain copyright

The author is the copyright holder until this is transfered to someone else. Publishers asks very soon after a paper is accepted for publication that the copyright be transfered to them. Typically, the form asks for all rights, which implies that the author cannot use her own work in other publication or in presentations, even in her own classroom. There are two ways to avoid this: 1) ask for the “other” copyright form, which publishers provides upon request only. This form allows the author to retain certain rights. 2) amend the copyright form. SPARC has developed a standard form that is available here [pdf]. See further details regarding this procedure.

Keep pre-prints online

In many cases, a paper was previously made available online as a working paper. Do not remove it. Indeed, you are the copyright holder and do not have to relinquish this. Even if you did not follow the steps above, in most cases, you can still keep your working paper online. Many publishers have made public that they tolerate, to various degrees, that these pre-prints remain in place. You can check this at SHERPA/RoMEO.

Provide post-prints

You can even archive so-called post-prints. These are accepted versions on your article. Many universities and research funders actually require that post-prints be publicly archived, for example in an institutional repository. In Economics, it is also common to publish an accepted work in a working paper series. Again, to see what publishers officially allow in this respect, see SHERPA/RoMEO. You have more rights, of course, if you took steps to retain them.

Leave a Comment » | Dissemination of research in Economics | Permalink
Posted by Christian Zimmermann

Volunteer appreciation: Venus Khim-Sen Liew

February 10, 2010

RePEc works thanks to a large number of volunteers, most of them toiling in anonymity. One who spends a lot of time on the project is Venus Khim-Sen Liew, currently Associate Professor of Economics at Universiti Malaysia Sarawak in Malaysia. Among many other professional responsibilities, he is editor at MPRA, the RePEc service that allows authors to upload their works to be indexed on RePEc, for those who do not benefit from a local RePEc archive. MPRA needs editors to ensure some quality control to make sure that submissions are of academic nature and satisfy copyright requirements. Venus is in charge of submissions in Malaya and in particular helps with those in English, of which a considerable number (over 9000) have been accepted so far, and much of it is the result of Venus’ work.

If you are interested in helping with RePEc as well, check out the volunteer opportunities.

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Posted by Christian Zimmermann

RePEc in January 2010

February 3, 2010

The big news for RePEc this month is the inauguration of a new RePEc service, EconomistsOnline, provided by Nereus who also contributes a major new archive of working papers to RePEc.

In terms of traffic, we counted 760,521 file downloads and 2,629,780 abstract views during the month. RePEc has welcomed 9 new archives: CASE (Poland), Johannes Gutenberg Universität Mainz, NEREUS, Universidade de Concepción, RSconsult, FrancoAngeli Editore, INFER, Agency for Economic Analysis and Forecasting (Bulgaria), Technological Educational Institute of Kavala

And finally, the thresholds reached during the month:

120,000,000 cumulated working paper abstract views
850,000 items listed
400,000 working paper announcements sent through NEP
333,333 working papers listed
275,000 working papers online
250,000 working paper abstracts
120,000 working papers with citations
4,000 series and journals listed

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Posted by Christian Zimmermann

Why and how RePEc is free

January 22, 2010

RePEc is allowing free access to its services, to readers, authors and publishers. Why? Because we want that research be disseminated the most widely possible and in the most democratic way possible. Everyone should have the same chance at getting read, no matter where the author is located. And everybody should be able to access research, no matter what the means and the location.

Of course, we cannot make research completely free, as some publishers keep their material gated. But whenever possible, we offer alternative, open access versions to gated material. Those versions may not be the latest ones, but they are usually close enough and usable by readers.

But how can we make all those services available for free? For one, we have volunteers who are willing to devote some of their spare time for the cause. Also, the running of RePEc is decentralized to the furthest extend possible. For example, the actual indexing is done by the publishers (following these instructions). As they are the ones who benefit the most from being listed, they are willing to comply with our requirements. Thus the data input is costless to RePEc, and then the collected data is made available to those who would like to build a service with it. Again, volunteers create and manage these services at no cost to RePEc.

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Posted by Christian Zimmermann

Poll on internal disclosure of author statistics

January 14, 2010

The statistics compiled by RePEc are used for various rankings, for example for authors. While we still consider these statistics to be experimental, in particular those pertaining to citations, these numbers are increasingly used for evaluation purposes. We value the privacy of authors and only disclose the statistics for the top ranked ones. Authors get each month a link to their statistics, a link with a code valid only for a month. This avoids a link that may have been disclosed once to be visible forever.

We get more a more requests from department heads to obtain the data for members of their department. Our typical response is to have them ask directly the members of their department to forward them their monthly RePEc emails. But of course, we could also provide directly all the relevant information. The purpose of this poll is to see whether participants in RePEc would favor such a disclosure. The conditions would be:


  1. The request must come directly from the head of the relevant department, by email to Christian Zimmermann
  2. The request contains a link allowing to verify that this person is indeed head.
  3. Statistics would be disclosed only for the members of the department who are currently affiliated with the department, as indicated in their RePEc profiles.
  4. Those with invalid email addresses would be excluded from the analysis, under the presumption that their affiliation may not be current.
  5. The department head would be provided with a link containing the analysis, a link that expires with the next monthly update of the rankings.
  6. The department head needs to be a registered author.
  7. A department would receive at most one disclosure a year.
  8. We reserve the right to refuse disclosing statistics.
  9. By department, we mean any unit with a separate entry in EDIRC.

If you have an opinion about thus please vote below and/or offer a comment. Given the nature of the question, we would require significant more than a majority (two thirds) to offer this service. The poll closes on February 21, 2010.

Update (22/2/2010): This poll is now closed. There was little interest, with only 89 votes, which fell 52-37 in favor of the disclosure. With an approval rate of 58%, it fell short of what I consider a substantial majority for an implementation. Thus, there will be no disclosure to department heads.

Leave a Comment » | RePEc rankings, Use of RePEc data | Permalink
Posted by Christian Zimmermann

RePEc in December 2009, and a look back at 2009

January 7, 2010

And another year came to a close, with RePEc celebrating 1/8 of a century since its founding. But let us first have a look at we was done in the last month. We welcomed 8 new archives: Colegio de economistas de A Coruna, Universidad de Oviedo, Revista de Economia Aplicada, National University of Ireland, Galway, Certified General Accountants Association of Canada, George Zane Institute for Economic and Social Research, China Agricultural University, Basque Centre for Climate Change. Despite this relatively small number of newcomers, over 11,000 new works were added, bringing up the number of listed full texts to over 700,000. Traffic was also high for December, with 714,638 file downloads and 2,519,682 abstract views.

As for 2009, what have we achieved? 150 new archives, 142,000 newly listed works (+21%), of which 133,000 are available online (+23%), 4,000 new registered authors (+22%). I would argue this is tremendous growth for a project that is already 12.5 years old. We started a research blogging initiative, introduced a Facebook application. We counted 9,540,461 downloads and 34,024,922 abstract views.

And let me conclude with the thresholds attained during the last month:
1,000,000 chapter abstract views
700,000 listed full texts
275,000 cited items
200,000 cumulative book downloads
5,000 listed books

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Posted by Christian Zimmermann

Statistics delay

January 1, 2010

The December 2009 statistics, as well as a look back at 2009, will be posted a few days late, as we are attending the ASSA meeting in Atlanta. Stop by at our booth in the exhibitors hall to say hello and discuss about RePEc.

NB: the monthly emails to authors, editors and series maintainers will also be delayed by a few days.

Leave a Comment » | Temporary RePEc announcements | Permalink
Posted by Christian Zimmermann

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