We find Nature Research's critical attitude towards journal impact factors, embodied in its signing of the San Francisco Declaration on Research Assessment (DORA; Nature 544, 394; 2017), to be inconsistent with the aims of its Nature Index.

The Nature Index provides statistics on the publication output of institutions and countries. These statistics are collated from “high-quality research” published in an independently selected set of 68 “high-quality science journals” (see www.natureindex.com/faq). The data are presented as metrics that can be used to assess “research excellence and institutional performance”.

This seems to us to be in violation of DORA's principles, which state that research should be assessed “on its own merits rather than on the basis of the journal in which the research is published” (www.ascb.org/dora).

Even though we disagree with some of the ideas underlying DORA (see L. Waltman and V. A. Traag, preprint at arxiv.org/abs/1703.02334; 2017), we believe that Nature Research should practice what it preaches and abandon the Nature Index.

On behalf of the Nature Index, David Swinbanks replies — The Nature Index provides an indicator of an institution's contributions to high-quality research, on the basis of papers from a suite of journals that exhibit high editorial standards and have been independently chosen by a committee of active researchers — without regard to impact factor (see go.nature.com/2qo53pj). The Nature Index enables the tracking of institutional research output and collaboration at the city, state and country levels.

It is therefore not in violation of DORA, which champions appropriate ways of appraising individual researchers and opposes the abuse of the journal impact factor as a metric for research assessment.