Skip to main content
. Author manuscript; available in PMC: 2018 Nov 10.
Published in final edited form as: Stat Med. 2017 Jul 31;36(25):4041–4049. doi: 10.1002/sim.7414

Table 3.

Compare one-shot nonparametric method and IPCW method. Change point Cox PH model: covariates X and Y are generated from Uniform[0, 1]. Parameters in hazard function are λ0 = 0.01, β1 = 3, β20 = 0.1, and β21 = 15. The change point τ = 8.59 is selected such that CTX = CTY = 0.655 based on 100,000 simulations. The values of parameter λ for exponential censoring is chosen to achieve the desired censoring proportions. Threshold model: event time T is generated from exponential distribution with the rate λ =1. Two risk scores X and Y are generated from a mixture of bivariate normal distribution described in equation (7), with parameters μ0 = 2, ρ = 0, σ12=9 and σ22=0.25. The cut point τ = 0.718 is selected such that CTX = CTY = 0.803 based on 100,000 simulations. Parameters λ for exponential censoring is chosen to achieve the desired censoring proportions. Sample size n=100.

The one-shot nonparametric method The IPCW method
% Censor ĈTX ĈTY ĈTXĈTY % Reject H0
at α = 5%
% Reject H0
at α = 10%
TX TY TXTY % Reject H0
at α = 5%
% Reject H0
at α = 10%
n=100

Change point model 0% 0.657 0.660 −0.003 5.0% 9.8% 0.661 0.659 0.002 4.6% 9.1%
10% 0.663 0.647 0.016 6.4% 11.8% 0.661 0.659 0.002 4.2% 8.3%
20% 0.669 0.633 0.036 10.5% 18.0% 0.661 0.658 0.002 3.6% 7.3%
33% 0.68 0.612 0.068 21.9% 31.6% 0.661 0.659 0.002 2.7% 5.7%
50% 0.695 0.582 0.113 39.4% 51.6% 0.661 0.658 0.003 1.7% 4.1%
   65% 0.710 0.563 0.147 47.2% 59.5% 0.663 0.657 0.006 1.3% 3.1%
80% 0.720 0.565 0.156 36.3% 48.4% 0.682 0.656 0.027 1.2% 2.7%

Threshold model 0% 0.802 0.802 0.000 5.4% 10.2% 0.803 0.802 0.001 4.9% 9.8%
10% 0.816 0.803 0.013 7.2% 12.6% 0.803 0.802 0.001 4.5% 8.8%
20% 0.830 0.805 0.025 10.7% 18.0% 0.803 0.802 0.001 3.8% 7.5%
33% 0.852 0.808 0.044 20.9% 30.9% 0.805 0.802 0.003 3.3% 6.9%
50% 0.884 0.818 0.066 40.0% 52.4% 0.809 0.803 0.006 2.1% 5.2%
65% 0.918 0.834 0.083 57.1% 69.7% 0.821 0.803 0.018 4.7% 8.0%
80% 0.955 0.865 0.090 65.5% 77.8% 0.863 0.802 0.061 10.2% 17.6%