This edition of the BJA sees the publication of Kluyt et al’s manuscript detailing the development and internal validation of the ASOS surgical risk calculator. (1) This publication arises from the African Surgical Outcomes Study (ASOS), (2) which recorded prospective risk and outcome data on 11,422 adult patients undergoing surgery in 247 hospitals from 25 countries on the African continent. This was a complex endeavour, which required excellent coordination and leadership as well as the unpaid contribution of more than a thousand healthcare professionals working in very challenging conditions. For this substantial effort in the spirit of ‘citizen science’, and the quality of the outputs so far, the authors and collaborators are to be congratulated.