Keywords: geosampling, sampling methodology, fieldwork

ORB International has been using gridded population frames generated based on 2023 Global Human Settlement Layer GHS-POP gridded population datasets and augmented by additional geodata. The process generates PSU shapes based on 1) a target population of 1200; 2) that don’t exceed a certain size (5 sq km); and 3) that don’t cross over administrative districts or urbanity designations. However, ORB’s experience indicates that the frames needed additional review to establish viability (the likelihood that each PSU has enough population to sample according to project methodology) and accessibility (the local team ability to safely and practically get to the PSU in question and conduct the fieldwork). In this study, we summarize key learnings from implementing these frames in Senegal, Nigeria, Chad, Somalia, and Mali, focusing on the PSU review process and fieldwork efficiency. We share the lessons learned in preparation of the sample as well as implementation, including training on-the-ground team for the sample review and the implementation of gridded population sampling.