Fig. 1
From: Design of trials for interrupting the transmission of endemic pathogens
Schematics of three SWCRT design sequences on a grid of 81 equal-area clusters. Clusters are numbered in the order of the design rollout sequence. In the diagram as shaded, clusters 1–20 have received the intervention and clusters 21–81 have not yet received the intervention. All sequences begin at one randomly selected cluster. a Hierarchical SWCRT sequence: the sequence begins at one randomly selected meta-cluster. Clusters within that meta-cluster are filled in a random order until the meta-cluster is complete, then the next meta-cluster is selected. b Oil-drop SWCRT sequence: the sequence begins at one randomly selected cluster and spreads across adjacent clusters until the grid is filled. c Random SWCRT sequence: clusters are selected at random until the grid is completely filled. For all SWCRT designs, by the end of the intervention rollout there will be an equal number of cluster-days with and without the intervention. However, at almost all time points during the rollout, the populations in the two study arms will be unequal. SWCRT stepped wedge cluster randomized trial