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Relative efficiency (of unequal clusters) for a crossover layout (solid line) and some parallel (dotted lines) and stepped wedge (broken lines) layouts for the Hussey and Hughes model (π = 1, τ = 0) under a Gamma distribution for cluster size with CV2 = 0.5. The horizontal axis represents a transformed version of the average cluster size (m) and ICC (ρ), as described in the text
