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Table 2 Impact of trial design on the median and inter-quartile range of possible efficiency of a SW-CRT with unequal cluster size compared so a SW-CRT with equal cluster size

From: The impact of varying cluster size in cross-sectional stepped-wedge cluster randomised trials

CV CMC SW3 SW12 PD
12 clusters 96 clusters 12 clusters 96 clusters 12 clusters 96 clusters
0.25 0 1.00 (0.98–1.07) 1.00 (0.99–1.01) 1.00 (0.97–1.02) 1.00 (0.99–1.01) 1.00 (0.99–1.00) 1.00 (1.00–1.00)
0.2 0.99 (0.98–1.04) 1.00 (0.99–1.00) 0.99 (0.98–1.01) 1.00 (0.99–1.00) 0.99 (0.98–0.99) 0.99 (0.99–0.99)
0.5 0.99 (0.98–1.02) 1.00 (0.99–1.00) 0.99 (0.98–1.00) 0.99 (0.99–1.00) 0.99 (0.98–0.99) 0.98 (0.98–0.99)
0.8 1.00 (0.99–1.01) 1.00 (1.00–1.00) 0.99 (0.99–1.00) 1.00 (1.00–1.00) 0.99 (0.99–0.99) 0.99 (0.99–0.99)
0.75 0 0.97 (0.90–1.02 1.00 (0.98–1.01) 0.96 (0.90–1.02) 0.99 (0.97–1.02) 0.98 [0.94–1.00) 1.00 (0.99–1.00]
0.2 0.95 (0.90–0.99) 0.97 (0.96–0.98) 0.94 (0.89–0.99) 0.96 (0.95–0.98) 0.91 (0.88–0.94) 0.92 (0.91–0.93]
0.5 0.95 (0.91–0.98) 0.97 (0.96–0.98) 0.94 (0.90–0.97) 0.96 (0.95–0.97) 0.88 (0.85–0.91) 0.88 (0.87–9.90)
0.8 0.96 (0.92–0.99) 0.99 (0.98–0.99) 0.96 (0.93–0.97) 0.98 (0.98–0.99) 0.90 (0.88–0.93) 0.93 (0.89–0.91)
1.25 0 0.91 (0.79–1.00) 1.00 (0.95–1.02) 0.89 (0.78–0.99) 0.98 (0.94–1.02) 0.94 (0.82–0.99) 0.99 (0.98–1.00)
0.2 0.88 (0.78–0.95) 0.93 (0.91–0.95) 0.85 (0.76–0.93) 0.92 (0.90–0.94) 0.81 (0.74–0.86) 0.82 (0.80–0.83)
0.5 0.88 (0.79–0.93) 0.93 (0.91–0.95) 0.85 (0.79–0.90) 0.91 (0.90–0.92) 0.73 (0.67–0.78) 0.73 (0.71–0.75)
0.8 0.90 (0.81–0.95) 0.96 (0.95–0.98) 0.88 (0.83–0.92) 0.95 (0.94–0.96) 0.76 (0.70–0.81) 0.75 (0.73–0.77)
  1. CMC Cluster mean correlation, CV coefficient of variation in cluster sizes, SW3 Stepped-wedge trial with 3 sequences, SW12 Stepped-wedge trial with 12 sequences (one cluster per sequence), PD Parallel design