English: Two possible occurrences for a two-stage trial: stopping at stage one (top) and stopping at stage two (bottom). For the top example, the data available at the interim analysis provides enough information to stop the trial, either for futility or benefit, and the interim analysis is the final analysis. For the bottom example, the data available at the interim analysis does not provide enough information to stop the trial, and the trial continues: more participants are recruited, and final analysis is undertaken when data are available for all participants.