My citation count just went down!

May 26, 2012

We sometimes get angry emails from authors pointing out that their citation count decreased. And this is quite understandable, as no one likes to see decreasing citation numbers. But it can happen, and most of the time it is for very legitimate reasons, not some conspiracy. Here is a rundown.


  1. A citing or cited item has been removed from RePEc. This is rare but does happen on occasion. We recommend against removing item in general, as discussed in a previous blog post. Hint: the fact that a working paper got published in a journal is very rarely a reason to remove its link to full text, let alone its entire entry.
  2. A RePEc archive renumbers its handles. A handle is the identifier of every item in RePEc. It is supposed to be unique and permanent, yet every month some archive has the bright idea to renumber its material. The consequence: the citation analysis needs to be completely redone, and all the other links as well. This leads to a temporary decrease in citation numbers.
  3. When different versions of some work are linked, citations are consolidated. Thus what counted as separate citations now only counts as one. And this version consolidation can happen for the citing or the cited work.
  4. The author removed some work from the author profile, for example when a paper got published. Citations to the working paper version are then temporarily lost until the article is indexed in the citation service.
  5. An error with RePEc. This can happen despite our best efforts, and it always has been temporary.

And lastly, the citation count in the statistics sent to authors is different from what you see on the web at IDEAS or the RePEc Author Services: this is because multiple versions of the same work are aggregated, and because self-citations do not count.

Leave a Comment » | Bibliographic features in RePEc | Permalink
Posted by Christian Zimmermann

On RePEc traffic numbers

May 19, 2012

RePEc provides traffic statistics to authors, editors, and archive and series maintainers. LogEc displays them to the public. These downloads and abstract views are obtained from some, but not all, RePEc services which compile their server log files: Economists Online, EconPapers, IDEAS, NEP and Socionet. The raw logs are purged from anything that does not look like human traffic (robots, spiders), repeat traffic as well as anything that does not seem licit. This typically divides traffic numbers by four or five. More details are available at LogEc.

Several people have noticed that RePEc traffic numbers have exhibited a downward trend over the last couple of years. We do not have a definite answer, but we have a few possible explanations for this trend.

Tightening of criteria

The criteria for what is considered licit traffic have been tightened in July 2010, retroactively to January 2008 (see blog post). This can explain a one-time decrease in reported traffic, but not the trend.

Server caches

We noticed that several institutions run server caches of IDEAS. This means that any request to an IDEAS page comes from this server, and thus requests from separate people count as one. Worse, if there are many such requests, the server is considered a robot and none count. While this has an impact on traffic numbers, it is not believed to be a major impact.

Proxy servers

These are servers through which all web traffic of an institution is routed. The main goal is security: all computers behind the proxy server appear to have the same IP address, and a potential attacker cannot find the individual IP addresses. The impact is the same as with the above: all traffic from an institution (for example the hundreds of economists from the US Federal Reserve System) are considered to be from a single person, and possibly a illicit robot. This can explain stagnating traffic and, if the adoption of proxy servers is increasing, even decreasing traffic.

Non-reporting RePEc services

Several RePEc services are not reporting traffic logs to LogEc. If they are diverting traffic away from reporting services, the visible statistics suffer. As RePEc is getting used more and more by bibliographic services, the declining recorded traffic gives then a false image of the evolution.

Google Scholar priorities

Substantial traffic is coming from Google Scholar, which used to rely substantially on RePEc for its initial launch, at least for economics material. As Google established partnerships with commercial publishers, commercial material is now privileged in search results and RePEc is often confined to the much less prominent “other versions.”

Better usage

It could also be that users are getting more efficient at finding what they are looking for, either because they are getting better at it, or because the RePEc services have improved their websites. If one needs to read fewer abstracts until one finds the right works, this will lower traffic and increase user satisfaction.

Reduced popularity

Finally, it could be also that RePEc services are becoming less popular, given the existence of several good alternatives (which are almost all using RePEc data). The fact that raw traffic, which includes all that LogEc eliminates, is still going up would invalidate this argument, unless this increase is entirely due to an increase in robot traffic.

All in all, we are not sure why we have the decrease in the “visible” traffic numbers. Maybe our loyal readers have further suggestions.

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

RePEc in April 2012

May 3, 2012

The innovation of the month is the complete overhaul of EconAcademics.org, the blog aggregator for economics research. It now monitors a much longer list of blogs and selects the blog posts that discuss research. Also, IDEAS now links back from the abstract and author pages to the posts.

We counted 634,507 file downloads and 2,319,912 abstract views during last month and welcomed the following new participating RePEc archives: Kasetsart University, Review of Agrarian Studies, Brigham Young University, Karl-Franzens-Universität Graz, Bahcesehir University, JICA Research Institute, La Trobe University (II), Western Risk and Insurance Association, IGI Global, Barcelona Graduate School of Economics, Universitatea Andrei Saguna, Scientific Society of Management from Romania, Duke University (II), and Università di Trieste.

Finally, we passed the following thresholds:
3000000 matched citations
2500000 cumulative downloads through NEP
2000000 cumulative abstract views for book chapters
700000 listed articles

Leave a Comment » | Workings of RePEc | Permalink
Posted by Christian Zimmermann

How does RePEc get its data?

April 24, 2012

The RePEc team regularly gets requests to from authors to add this or that item to the database, or enquiries from editors why RePEc is discriminating against their journal by not listing it. It is therefore useful to discuss again how RePEc gathers all its bibliographic data, and thus what various users can do to enhance the listings.

RePEc does not have any data entry staff, one because RePEc has a budget of zero, two because the data entry is done by the respective publishers. The same rules apply to all, whether it is a large commercial publisher with many journals or a small research center with a working paper series: they have to open a local metadata archive with bibliographic information formatted in a way that RePEc services can automatically gather and analyze on a regular basis (usually every night). So far, over 1400 archives have followed the detailed instructions necessary for participation. Authors with institutions that fail to participate in RePEc can still get their work listed, by uploading it with MPRA. They need copyright clearance for this, which is granted by most publishers, according to the list compiled by SHERPA/RoMEO.

Author profiles are also maintained by the authors themselves, by registering at the RePEc Author Service. The citation analysis (CitEc project) also depends on the collaboration of publishers, either by allowing the free download of the full texts or by providing the metadata about references separately.

The extremely decentralized nature of RePEc is what allows to reduce central costs to almost nothing and thus keep RePEc free for all: publishers, authors, and readers. The collected data can then be offered by the various RePEc services, and those bear the (small) cost of massaging the RePEc data to make it useful for everyone.

4 Comments | Dissemination of research in Economics, Workings of RePEc | Permalink
Posted by Christian Zimmermann

Aggegating discussion of economics research on blogs

April 10, 2012

The discussion of economic issues on the blogosphere is too little based on actual research. To promote blogs that discuss research, the blog aggregator EconAcademics.org was created a few years ago, showing for a select few blogs their last posts. EconAcademics.org has now been completely redone, with a radical change in concept.

The site now monitors a large number of economics blogs and selects the posts that discuss research. These posts are currently identified by a link to material on EconPapers, IDEAS, or NEP. The selected posts are then displayed on the site (main page and respective language) and linked from the relevant IDEAS page. We hope this will further promote the discussion of economic issues based on research and the blogs that do so.

You can find the new blog aggregator at EconAcademics.org.

1 Comment | Dissemination of research in Economics, Use of RePEc data | Permalink
Posted by Christian Zimmermann

RePEc in March 2012

April 5, 2012

The big news this month is the launch of a new RePEc service, CollEc, which analyzes co-authorship networks within RePEc. Data from CollEc is now also integrated in author rankings. Furthermore, IDEAS now links back to any Wikipedia article mentioning a RePEc page (details). And the RePEc home page was redesigned. Watch this space, more initiatives are on the way.

We counted 684,729 file downloads and 2,385,381 abstract views through reporting RePEc services. We also welcomed the following new participating RePEc archives: Cornell University (II), Central European Labour Studies Institute (CELSI), ISTIEE, Universidade de Vigo, Kammer für Arbeiter und Angestellte für Wien, and Okan Üniversitesi.

Finally, we passed the following thresholds:
150000000 cumulative working paper abstract views
300000 JEL coded items
40000 registered people

Leave a Comment » | Workings of RePEc | Permalink
Posted by Christian Zimmermann

Upcoming changes to rankings

March 26, 2012

The RePEc rankings are among the most visited pages of any RePEc service. While most of those rankings are still experimental and in some cases quite volatile (mostly due to incomplete citation data and not everyone being registered), they have proven to be extremely popular in the profession. While it is generally a bad idea to change definitions in the computation of rankings, sometimes there are good reasons to make adjustments or include more information. Two such changes will happen starting with the next release early April.

User-supplied weights for multiple affiliations

Authors with multiple affiliations currently have their scores distributed across affiliations for institutional rankings. The same applies across the geographic regions associated to each affiliation for the author rankings within regions. This is not going to change. But now that authors can set these weights themselves, author-supplied ones will be used if present. If not, the weights will continue to to be determined according to a formula that is supposed to determine the likelihood of a particular affiliation being the main one. In short: if you have multiple affiliations, set the weights yourself and the rankings will now take it into account.

Two new criteria for authors

The two rankings provided by CollEc, which measure how central an author is in Economics by looking at co-authorship networks, are going to be included for authors. As this concept is not well defined for institutions and regions, it will not be applied for those rankings. As the CollEc rankings change daily, a snapshot will be taken every month the day the new general rankings are produced. As not everyone can be ranked (see blog post for explanation), the unlisted will be ranked just below the last ranked author. These two new rankings will provide even more diversification to the ranking criteria.

Leave a Comment » | RePEc rankings | Permalink
Posted by Christian Zimmermann

Wikipedia and RePEc

March 19, 2012

Wikipedia is a well known crowd-sourced encyclopedia. It has an incredible wealth of knowledge which is often backed up by appropriate citations. Those citations may lead to material listed on RePEc. In fact, Wikipedia is currently the most important referrer to IDEAS (excluding search engines) and there are currently 1516 links to IDEAS and EconPapers, mainly on Wikipedia, and also on a few other projects, like Wikibooks, Wikiversity and Wiktionary. This number is gathered from the 57 languages with the most pages on Wikipedia. Of the 1524, 1363 resolve to author, book, article, chapter, software component or paper pages on IDEAS or EconPapers. The rest are mostly to service portals or to rankings.

The fact that a paper is mentioned in Wikipedia is not unlike a citation. Hence, IDEAS now links back to the appropriate Wikipedia page whenever possible. This can be found on the “lists” subfield on every IDEAS page. And for those curious about the distribution by language for the back-links: English 574, German 165, Spanish 83, Norwegian 48, French 48, Japanese 44, Bulgarian 41, Turkish 36.

7 Comments | RePEc features | Permalink
Posted by Christian Zimmermann

A new RePEc service: CollEc

March 11, 2012

A new RePEc service is now on-line, CollEc. The main goal of this initiative is to analyze co-authorship networks within Economics. To this end, it collects all the authorship data from the RePEc Author Service and computes the shortest path through co-authorship relationships between any two registered economists. From all this data, two “features” are computed.

First, a closeness and a betweenness score is computed for every economist. Closeness measure how close one is with everyone else. Betweenness measures how frequently shortest paths have a particular economist as a node. Of course, economists can be ranked according to both criteria.

Second, the website allows to display the shortest paths between any two economists, and one can be surprised at how short they often are. To play with this, either navigate the lists on CollEc or find the direct link to an author’s page on IDEAS (author profile, under “statistics”), then enter the name of another author.

Note that only authors registered with RePEc are considered. Also, not every registered author is part of this global network of co-authorship. For example, an author without a (registered) co-author is excluded. Also, an economist at the end of a path cannot have a betweenness score, mostly likely someone with a single (registered) co-author.

2 Comments | RePEc features, Use of RePEc data | Permalink
Posted by Christian Zimmermann

RePEc in February 2012

March 2, 2012

The big news this month are the release of an upgrade of the RePEc Author Service and the new layouts of IDEAS and EDIRC. We hope this will improve the satisfaction of our many users, who were responsible for 642,216 file downloads and 2,276,448 abstract views. This leads us to the next big news: since the start, a quarter billion abstract views have been counted by the statistics-reporting RePEc services.

We also want to welcome the following new participating archives: International School for Social and Business Studies (Slovenia), University of Warwick (III), Università di Roma La Sapienza (IX), University of Toronto (III), Copernicus University in Torun (Poland), Columbia University (II), Banco Central de la Republica Argentina, Auckland University of Technology, Université d’Aix-Marseille, and St. Olaf College.

Finally, we have reached the following thresholds, and the list is long:
250000000 cumulative abstract views
25000000 cumulative article downloads
7500000 references extracted from documents
3000000 references matched with documents in RePEc
750000 item abstracts
250000 JEL coded items
200000 JEL coded papers
70000 NEP subscriptions
12500 listed institutions
10000 book abstracts
1400 participating archives

Leave a Comment » | Workings of RePEc | Permalink
Posted by Christian Zimmermann

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