In November 2014, the Nature Index (NI) was introduced (see http://www.natureindex.com) by the Nature Publishing Group (NPG). The NI comprises the primary research articles published in the past 12 months in a selection of reputable journals. Starting from two short comments on the NI (Haunschild & Bornmann, , ), we undertake an empirical analysis of the NI using comprehensive country data. We investigate whether the huge efforts of computing the NI are justified and whether the size‐dependent NI indicators should be complemented by size‐independent variants. The analysis uses data from the Max Planck Digital Library in‐house database (which is based on Web of Science data) and from the NPG. In the first step of the analysis, we correlate the NI with other metrics that are simpler to generate than the NI. The resulting large correlation coefficients point out that the NI produces similar results as simpler solutions. In the second step of the analysis, relative and size‐independent variants of the NI are generated that should be additionally presented by the NPG. The size‐dependent NI indicators favor large countries (or institutions) and the top‐performing small countries (or institutions) do not come into the picture.