The impact of varying cluster size in cross-sectional stepped-wedge cluster randomised trials.
James Thomas MartinKarla HemmingAlan GirlingPublished in: BMC medical research methodology (2019)
The actual realised power in a stepped-wedge trial might be substantially higher or lower than that estimated. This is particularly important when there are a small number of clusters or the variability in cluster sizes is large. Constraining the randomisation on cluster size, where feasible, might mitigate this effect.