Pros and cons of supplementary materials in scientific publishing

Dave Shutler and Ashley Murray of Nova Scotia's Acadia University analyzed trends in the use of supplementary materials since 2000 in 13 journals widely read by ornithologists. Ten showed significant increases in the use of supplementary materials over time, in some cases with a corresponding decrease in appendices, which (unlike supplementary materials) are included in print versions of journals.

Papers with supplementary materials add complexity to every step of the publication process. They place additional demands on authors, who must decide what's relevant enough to include and spend time preparing and submitting the materials; reviewers, who already volunteer their time to ensure the quality of published studies and who in some cases refuse to review supplementary materials; and journal production teams, who must spend time copyediting and formatting the materials. Navigating journal websites to find supplementary materials can be time-consuming and frustrating for readers, especially those who prefer to work with print copies of studies.

However, supplementary materials can add value as well. They give researchers almost unlimited capacity to publish information relevant to a study, reduce printing costs, and make it possible to publish material that can't be included in print, such as sound and video files. "My hope is that, among other things, we will all take a step back and evaluate what belongs as supplementary materials and how much we want to invest in ensuring that supplementary materials are legitimate contributors to advancing science," says Shutler.

"No one writes about the role of supplementary materials," adds Auk Editor-in-Chief Mark Hauber. "The phenomenon just happened and now we all have to live with it. It's surprising to think that in an era of online publishing, we should need unreviewed sections of papers to be available to understand the reviewed components of the paper."