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. Author manuscript; available in PMC: 2016 Jun 30.
Published in final edited form as: Stat Med. 2015 Mar 20;34(14):2235–2265. doi: 10.1002/sim.6470

Table 1.

Bias in estimating log causal hazard ratio parameter (ρa = 0, ρc = 0.5, ρr = 0.8, θc1=3.33, θc0=1.67)

α δ
Bias2spsanalytic
Bias2spsAFT
Bias2spsCox
Bias2srianalytic
Bias2sriAFT
Bias2sriCox
0.5 2 -0.094 -0.093 -0.091 -0.477 -0.476 -0.476
1.5 -0.067 -0.068 -0.064 -0.238 -0.239 -0.235
1 -0.039 -0.040 -0.039 -0.086 -0.087 -0.086
0.5 -0.013 -0.016 -0.012 -0.015 -0.018 -0.014
0 0.007 0.009 0.007 0.000 0.002 0.000
-0.5 0.023 0.020 0.026 0.000 -0.003 -0.001
-1 0.038 0.037 0.051 0.029 0.028 0.029
-1.5 0.055 0.053 0.075 0.114 0.112 0.108
-2 0.073 0.074 0.101 0.261 0.263 0.236

1 2 -0.250 -0.253 -0.247 -0.545 -0.550 -0.544
1.5 -0.177 -0.175 -0.177 -0.285 -0.284 -0.284
1 -0.096 -0.093 -0.097 -0.110 -0.107 -0.112
0.5 -0.017 -0.020 -0.018 -0.022 -0.025 -0.023
0 0.051 0.053 0.055 0.000 0.002 0.000
-0.5 0.107 0.106 0.116 -0.007 -0.008 -0.009
-1 0.152 0.153 0.177 0.000 0.000 0.002
-1.5 0.193 0.191 0.232 0.057 0.053 0.055
-2 0.230 0.232 0.280 0.175 0.176 0.157

1.5 2 -0.422 -0.423 -0.418 -0.605 -0.607 -0.602
1.5 -0.285 -0.285 -0.284 -0.326 -0.325 -0.326
1 -0.132 -0.133 -0.134 -0.133 -0.134 -0.134
0.5 0.019 0.023 0.021 -0.028 -0.027 -0.029
0 0.153 0.152 0.159 0.000 -0.004 0.000
-0.5 0.261 0.266 0.274 -0.015 -0.012 -0.015
-1 0.345 0.342 0.376 -0.030 -0.033 -0.027
-1.5 0.412 0.412 0.461 -0.005 -0.008 -0.002
-2 0.467 0.468 0.531 0.078 0.075 0.068

2 2 -0.574 -0.578 -0.571 -0.656 -0.656 -0.653
1.5 -0.359 -0.360 -0.357 -0.362 -0.361 -0.359
1 -0.122 -0.124 -0.122 -0.152 -0.153 -0.152
0.5 0.111 0.115 0.112 -0.034 -0.032 -0.036
0 0.317 0.320 0.324 0.000 0.003 0.002
-0.5 0.481 0.479 0.494 -0.022 -0.026 -0.026
-1 0.605 0.605 0.636 0.059 -0.059 -0.056
-1.5 0.698 0.701 0.747 -0.069 -0.069 -0.063
-2 0.769 0.770 0.833 -0.023 -0.024 -0.026

Bias2spsanalytic - bias computed using analytic formula derived for 2SPS method; Bias2spsAFT - bias computed via simulation for 2SPS Weibull accelerated failure time model; Bias2spsCox -bias computed via simulation for 2SPS Cox model; Bias2srianalytic - bias computed using analytic formula derived for 2SRI method; Bias2sriAFT -bias computed via simulation for 2SRI Weibull accelerated failure time model; Bias2sriCox -bias computed via simulation for 2SRI Cox model;