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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