Fig. 2

Schematic diagram of the simulation considering the follow-up period and the timing of trial entry. White cells correspond to the control condition and grey cells to the intervention condition. Cross marks show examples of the time points when the five subjects in each cluster entered the trial. \(F\) is a coefficient that specifies the follow-up period that may be set after the end of the last step period. When \(F=0\), there is no follow-up period, and \({t}_{F}={t}_{E}\). If \(F=X(>1)\), there is a follow-up period of \(X\) step after the end of the last step period. \(E\) is a coefficient that specifies the timing of the trial entry. If \(E=1\), the subject enters the trial randomly between \({t}_{S}\) and \({t}_{E}\) or \({t}_{F}\), which reflects the open cohort design in that the subject may enter in the trial at any time. If \(E\) is greater than 1, it reflects a situation where the entry of the trial is concentrated at an earlier stage of the trial. a Example of a case where \(F=3, E=1\), and trial entry is allowed until the follow-up period. b Example of setting \(F=3, E=1\) and trial entry is terminated in the final step period. c Example of setting \(F=0, E=2\). d Example of setting \(F=3, E=2\)