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. Author manuscript; available in PMC: 2019 Aug 30.
Published in final edited form as: Stat Med. 2019 May 6;38(19):3599–3613. doi: 10.1002/sim.8185

Table 3.

Simulation results under misspecification of the truncation distribution: Survival times simulated from a gamma(10, 1) distribution. Left and right truncation times assumed to come from a gamma(α1, β1) and gamma(α2, β2) distribution, respectively. Model 4 corresponds to misspecification of the right truncation time by simulating it as Unif(0, 20), and the left truncation time as gamma(3,1). Model 5 corresponds to misspecification of the left truncation time by simulating it as Weibull(1, 3), and the right truncation time as gamma(5, 2). Model 6 corresponds to misspecification both truncation times by simulating the left truncation time as Weibull(1, 3) and the right truncation time as Unif (0, 20). Here qL, qR, q are the proportion of observations missing due to left, right, and double (left and right) truncation, respectively, and n is the size of the observed sample. F^SP denotes the SPMLE, F^NP denotes the NPMLE, and F^emp denotes the naïve empirical CDF which ignores double truncation. These estimators were all computed at t0.1,…, t0.9, the 1st through 9th deciles of the true survival distribution F0. For a given estimator F^, Bias(F^) is the (absolute) difference between F^ and F0, averaged across the 9 deciles. Here SD(F^) is standard deviation of F^ across simulations, SE^(F^) is estimated standard error of F^, MSE(F^,MSE(F^)) is mean squared error of F^, and Cov(F^) is 95% coverage, all averaged across the 9 deciles. Here t^0.5 is the estimated median value based on F^. The true median value based on F0 is t0.5 = 9.7. Here Bias(t^0.5) = t^0.5 - t0.5 and SD(t^0.5) is the standard deviation of t^0.5 across simulations.

Model qL, qR, q n Estimator Bias(F^) SD(F^) SE^(F^) MSE(F^) Cov(F^) Bias(t^0.5) SD(t^0.5)
F^SP 0.008 0.074 0.160 0.006 0.968 0.091 0.725
4 0.02,0.50,0.51 50 F^NP 0.023 0.075 0.068 0.006 0.878 0.017 0.734
F^emp 0.092 0.056 0.044 0.013 0.455 −0.848 0.461
F^SP 0.009 0.033 0.062 0.001 0.995 0.062 0.310
4 0.02,0.50,0.51 250 F^NP 0.007 0.033 0.033 0.001 0.932 −0.014 0.299
F^emp 0.091 0.025 0.020 0.010 0.301 −0.816 0.207
F^SP 0.011 0.084 0.098 0.008 0.886 0.032 0.841
5 0.06,0.52,0.56 50 F^NP 0.029 0.087 0.077 0.009 0.834 0.073 0.954
F^emp 0.144 0.054 0.042 0.026 0.441 −1.297 0.423
F^SP 0.007 0.038 0.037 0.002 0.921 −0.032 0.339
5 0.06,0.52,0.56 250 F^NP 0.008 0.040 0.039 0.002 0.921 −0.021 0.353
F^emp 0.144 0.024 0.019 0.024 0.331 −1.288 0.201
F^SP 0.009 0.073 0.168 0.006 0.961 0.047 0.698
6 0.06,0.50,0.53 50 F^NP 0.027 0.073 0.068 0.006 0.873 −0.030 0.659
F^emp 0.088 0.056 0.044 0.012 0.455 −0.826 0.476
F^SP 0.010 0.034 0.062 0.001 0.992 0.035 0.320
6 0.06,0.50,0.53 250 F^NP 0.009 0.035 0.032 0.001 0.924 −0.039 0.365
F^emp 0.086 0.025 0.020 0.009 0.301 −0.771 0.210