RePEc rankings: adjustments and novelties

March 26, 2010

Given the increased interest in the various RePEc rankings, as well as thanks to comments made by users, I have made various adjustments over the last months. Some are barely perceptible, while some give some new features. Here is a short list.

Aggregate ranking for series and journals
Thanks to popular demand, there is now a ranking that aggregates the four impact factors, the h-index, download counts and abstract views. This ranking is available for journals, working paper series and all series.
Linked series
By linked series, I mean the situation where a series ceased to exist and continues under a new name. This happens in particular for journals that switch publishers, or journals that merge. Various statistics are now merged for ranking purposes. Thus, there is now a unique impact factor for the various series or journals. This was more complex to pursue for the h-index, and obviously all affected series gained from that. However, this increased the scope of self-citations that could be removed for the impact factor calculations.
Note to RePEc archive maintainers: you can link your series or journals to others by adding a new field in your series templates, Followup: or Successor:, followed by the handle of the other series.
Expanded listings
Following a poll a few months ago, the portion of the rankings that is public has been expanded. This will be visible with the ranking released early next month. The ranking of authors and institutions within countries or US states passes from the top 20% to the top 25%, within fields from the top 5% to 10%. The big ones, the top 5% authors and institutions still includes the top 5% in much detail, but now also the next 5% in five 1% “bins.”
US Economics departments
While there is already a ranking of Economics departments, one of the most frequent requests is to have one specifically for the United States. There will be one starting with next month’s update. Link.
Lost authors
We sometimes lose track of some authors when their monthly messages bounce back. Typically this is because they have moved or died. In both cases, they should not be counting towards the ranking of the institutions they are affiliated with. For a few months now, they have not. By the way, you can help rectify their status or their address by alerting us. The list of lost authors is here. See also the known deceased authors.
Peer authors
Registered authors receive every month an email with an analysis of their rankings. This now also includes a list of about 20 peers that are similarly ranked.
There is no reason an erratum or a correction should count as an additional publication for an author. We now try to drop them from ranking considerations and also to link them to the original article.

Volunteer appreciation: Volker Schallehn

March 15, 2010

Volker Schallehn is librarian at the University of Munich, but not your normal librarian. He has always been very active in open access, the free dissemination of research. For example, he has set up the institutional archive for the University of Munich, now one of the larger ones in the world, and doing so got so familiar with EPrints that he contributed code to this open-source project, along with a German translation of its interface.

His involvement with RePEc started when we were looking for a successor to the Economics WPA, which was holding papers for authors whose institutions or publishers were not (yet) participating in RePEc. Ekkehart Schlicht had the idea to add another repository to those Volker was already managing, hoping to exploit returns to scale. Volker agreed, seeing the broader mission in this initiative. Thus in 2006, the Munich Personal RePEc Archive was born, which now houses over 11,000 works and continues to grow steadfastly.

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

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