Power curves for various error structures. Power plots using the signal from temozolomide/MGMT with different error structures are shown in all panels. Panels A, C and E are under equal correlation with ρ = 0.75, 0.5 and 0.25, respectively. Panels B, D and F are under exponential correlation with ρ = 0.75, 0.5 and 0.25, respectively. Panels G and H had error terms generated independently as normal and gamma, respectively.