Credit: illustration by lorenzo petrantoni

Every organization that funds research wants to support science that makes a difference. But there is no simple formula for identifying truly important research. And the job is becoming more difficult. As funding gets squeezed, scientists face stiffer competition for resources and jobs, and it becomes more crucial than ever to develop reliable ways of spotting and supporting the best work. This week, Nature examines how the impact of research is measured — and asks whether today's evaluation systems promote the most important science.

Nature special: Impact

A News Feature on page 288 examines how countries are assessing work through elaborate audit systems. Supporters say that these improve overall research quality, whereas critics charge that they eat up time and money and skew grants towards 'hot topics'. A second News Feature on page 291 looks at the influence of the leading journals, traditionally recognized as a filter for important research. That role is now being challenged by changes in the publishing industry. And a Careers Feature on page 397 discusses how grant applicants can articulate the potential impact of their research, as required by many granting agencies.

One way of assessing the influence of research is to track citations of papers, but there are concerns that such data are often proprietary and not easily evaluated, writes David Shotton on page 295. Shotton is the director of the Open Citations Corpus, a fledgling repository for open scholarly citation data. Researchers are increasingly producing output — data, videos and code, for example — that do not mesh well with older systems for evaluating scientific contributions. On page 298, Mark Hahnel, founder of figshare, an online tool that allows researchers to publish all their data in a citable, searchable and shareable manner, describes the complexities of tracking the impact of these diverse research products.

These stories and commentaries show how evaluation systems are having to evolve rapidly to keep up with changes in the way that science is practised and communicated (see Editorial, page 271). Separating the best from the rest has never been harder.