Correction to: Nature Methods https://doi.org/10.1038/s41592-019-0495-7, published online 29 July 2019.

In the version of this Article originally published, owing to a technical error the dash used to denote molecular complexes in equations 3, 5 and 17 was duplicated; the correct notation is ‘protein–RNA complex’ (equations 3 and 17) and ‘Mg–NTP complexes’ (equation 5). In the HTML version of Supplementary Fig. 4, the title should have started “Affinity (as dissociation constant, KD)…”. These errors have now been amended in all online versions.