I strongly believe in the value of openness and transparency, and I encourage the authors to make their data and analysis code publicly available. Over and above increasing the transparency and reproducibility of scientific findings as a whole, sharing data and code increases the visibility and impact of individual papers (McKiernan et al. 2016 eLife). Please see the standards of the Peer Reviewers’ Openness Initiative (https://opennessinitiative.org/the-initiative/) for guidelines.
I hope this is useful to others – so far this has always worked (but my N is pretty small).