Comparative validation of machine learning algorithms for surgical workflow and skill analysis with the HeiChole benchmark

•Open benchmark for surgical workflow and skill analysis: annotation of surgical phase, action, instrument presence and skill in 33 human in-vivo videos.•New insights on the state of the art including detailed performance analysis across methods: recognition F1-score up to 67.7% phase & 63.8% instrument, but only 23.3% action.•Online leaderboard continuously available via www.synapse.org/Heichole based on the unreleased test data.