Table 1 Posterior mean relative risk estimates for the raised-risk areas for the BYM model (average over replicate data sets). SF = 1 SF = 2 SF = 4 SF = 10 Raised-risk area θ = 1.5 θ = 2 θ = 3 θ = 1.5 θ = 2 θ = 3 θ = 1.5 θ = 2 θ = 3 θ = 1.5 θ = 2 θ = 3 Simu 1  10% area (E = 0.84) 1.01 1.02 1.06 1.01 1.02 1.12 1.01 1.03 1.20 1.01 1.07 1.40  25% area (E = 1.10) 1.03 1.04 1.10 1.00 1.03 1.15 1.01 1.05 1.28 1.02 1.09 1.52  50% area (E = 1.92) 1.02 1.05 1.15 1.00 1.05 1.28 1.02 1.08 1.46 1.03 1.16 1.79  75% area (E = 5.37) 1.03 1.05 1.31 1.03 1.07 1.55 1.04 1.12 1.86 1.05 1.33 2.35  90% area (E = 7.38) 1.03 1.07 1.34 1.03 1.10 1.62 1.04 1.15 2.07 1.07 1.40 2.47 Simu 2  1% cluster (Ē = 5.42) 1.04 1.08 1.45 1.04 1.14 1.76 1.05 1.23 2.11 1.09 1.45 2.43 Simu 3 θ* = 1.35 θ* = 1.65 θ* = 2.1 θ* = 1.35 θ* = 1.65 θ* = 2.1 θ* = 1.35 θ* = 1.65 θ* = 2.1 θ* = 1.35 θ* = 1.65 θ* = 2.1  20 × 1% clusters (Ē range: 0.77–11.6) 1.04 1.23 1.63 1.07 1.3 1.74 1.12 1.38 1.84 1.19 1.48 1.95