Today, the open-access publisher the Public Library of Science (PLoS; www.plos.org), announces the release of an expanded set of article-level metrics on its scientific and medical journal articles (some 14,000 articles across 7 titles*). The article-level metrics program was launched in March 2009, and with today's addition of online usage data, PLoS is transparently providing an unprecedented set of information on every published article. Such information will be of value to researchers, readers, funders, administrators and anyone interested in the evaluation of scientific research.
The PLoS article metrics include the new online usage data (HTML page views, PDF downloads and XML downloads) that are compliant with the industry standard, COUNTER 3.0 http://www.projectcounter.org/code_practice.html, as well as citation counts, comments, ratings, social bookmarks and blog coverage. Usage data will be updated daily and currently include more than four years of statistics from all seven peer-reviewed PLoS journals. With this growing and detailed set of metrics on every article, PLoS aims to demonstrate that individual articles can be judged on their own merits rather than on the basis of the journal in which they are published.
Because very few data have previously been made public by scholarly publishers, visitors to the journal sites will need help to understand these data. For example, it is clear from the PLoS data that online usage is dependent on the age of the article, as well its subject area. In order to place the new usage data in context, PLoS is therefore providing summary tables to allow users to see how an article compares with various average measures. For anyone wishing to examine the data in detail the complete raw data set is also available as a download.
PLoS is still in the early stages of the article-level metrics program, but this is the first attempt by a major publisher to place such a broad range of data on each article. PLoS therefore hopes that the provision of these data will encourage other publishers to make such data available, which will lead ultimately to broader improvements in scholarly communication and research assessment.
Further information can be found in this blog http://www.plos.org/cms/node/485, these Frequently Asked Questions (http://www.plos.org/about/faq.html#metrics), this explanatory website (http://article-level-metrics.plos.org/) or you can direct your specific question to alm@plos.org.
To see examples of articles with a broad range of article-level metrics, look at the 'Impact' tab of http://www.plosgenetics.org/article/metrics/info:doi/10.1371/journal.pgen.0030104 and http://www.plosone.org/article/metrics/info:doi/10.1371/journal.pone.0000443.
* Please note that currently usage data are only displayed for articles published after June 17th, 2005, which comprise more than 90% of published articles, and we aim to provide the data for the remaining articles in the near future.