When is an article actually published? An analysis of online availability, publication, and indexation dates

TL;DR

This study compares various publication-related dates for nearly 59,000 papers to identify a consistent proxy for online publication, highlighting discrepancies across publishers and proposing the date of the Version of Record as a standard.

Contribution

It introduces a standardized definition of online publication date based on the first availability of the Version of Record to improve bibliometric accuracy.

Findings

Significant differences exist between publishers in publication dates.

The online date of the Version of Record is recommended as a standard.

More transparency in reporting publication dates is needed.

Abstract

With the acceleration of scholarly communication in the digital era, the publication year is no longer a sufficient level of time aggregation for bibliometric and social media indicators. Papers are increasingly cited before they have been officially published in a journal issue and mentioned on Twitter within days of online availability. In order to find a suitable proxy for the day of online publication allowing for the computation of more accurate benchmarks and fine-grained citation and social media event windows, various dates are compared for a set of 58,896 papers published by Nature Publishing Group, PLOS, Springer and Wiley-Blackwell in 2012. Dates include the online date provided by the publishers, the month of the journal issue, the Web of Science indexing date, the date of the first tweet mentioning the paper as well as the Altmetric.com publication and first-seen dates. Comparing these dates, the analysis reveals that large differences exist between publishers, leading to the conclusion that more transparency and standardization is needed in the reporting of publication dates. The date on which the fixed journal article (Version of Record) is first made available on the publisher's website is proposed as a consistent definition of the online date.