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. 2008 Jun 4;9:261. doi: 10.1186/1471-2105-9-261

Table 1.

Empirical type-I error and power obtained in 1,000 simulations using the three different approaches: REX (iterative regression), PEMM (probe-specific mixture model) and threshold.

Type-I error Power (gains) Power (loses)



σβ σγ σε x¯alt REX PEMM REX PEMM thres REX PEMM thres
0.2 0.2 0.05 3.7 0.073 0.031 0.815 0.745 0.000 0.819 0.751 0.000
0.2 0.2 0.08 3.6 0.071 0.027 0.689 0.546 0.000 0.681 0.541 0.000
0.2 0.4 0.05 3.5 0.081 0.044 0.923 0.891 0.024 0.930 0.908 0.029
0.2 0.4 0.08 3.5 0.079 0.038 0.870 0.811 0.028 0.863 0.814 0.057
0.2 0.6 0.05 3.6 0.081 0.052 0.965 0.955 0.131 0.956 0.956 0.161
0.2 0.6 0.08 3.6 0.086 0.044 0.922 0.889 0.140 0.922 0.900 0.184
0.2 1.0 0.05 3.6 0.081 0.057 0.980 0.983 0.360 0.977 0.972 0.411
0.2 1.0 0.08 3.6 0.085 0.052 0.955 0.954 0.396 0.947 0.939 0.449
0.2 1.5 0.05 3.6 0.081 0.060 0.982 0.978 0.536 0.981 0.983 0.582
0.2 1.5 0.08 3.6 0.084 0.056 0.981 0.986 0.623 0.980 0.975 0.630
0.2 4.0 0.05 3.5 0.078 0.064 0.995 0.993 0.815 0.993 0.994 0.840
0.2 4.0 0.08 3.5 0.079 0.060 0.996 0.993 0.848 0.993 0.995 0.863

0.4 0.2 0.05 3.7 0.079 0.032 0.822 0.729 0.000 0.827 0.737 0.001
0.4 0.2 0.08 3.7 0.070 0.027 0.690 0.522 0.000 0.697 0.537 0.000
0.4 0.4 0.05 3.7 0.081 0.046 0.918 0.897 0.027 0.926 0.905 0.044
0.4 0.4 0.08 3.7 0.078 0.038 0.878 0.807 0.035 0.871 0.825 0.069
0.4 0.6 0.05 3.6 0.080 0.052 0.958 0.949 0.139 0.952 0.942 0.191
0.4 0.6 0.08 3.5 0.083 0.044 0.926 0.903 0.150 0.913 0.881 0.206
0.4 1.0 0.05 3.7 0.080 0.057 0.981 0.982 0.353 0.973 0.977 0.425
0.4 1.0 0.08 3.5 0.081 0.050 0.949 0.953 0.392 0.950 0.934 0.424
0.4 1.5 0.05 3.6 0.083 0.063 0.989 0.985 0.553 0.987 0.989 0.613
0.4 1.5 0.08 3.6 0.080 0.056 0.976 0.973 0.568 0.966 0.967 0.603
0.4 4.0 0.05 3.6 0.085 0.066 0.997 0.996 0.856 0.995 0.995 0.855
0.4 4.0 0.08 3.6 0.086 0.062 0.994 0.991 0.841 0.989 0.990 0.864

0.6 0.2 0.05 3.6 0.075 0.031 0.828 0.740 0.000 0.824 0.741 0.001
0.6 0.2 0.08 3.6 0.071 0.027 0.701 0.529 0.000 0.690 0.520 0.002
0.6 0.4 0.05 3.7 0.082 0.047 0.932 0.916 0.032 0.914 0.902 0.063
0.6 0.4 0.08 3.6 0.077 0.037 0.864 0.815 0.041 0.874 0.835 0.070
0.6 0.6 0.05 3.7 0.082 0.051 0.964 0.949 0.142 0.955 0.944 0.174
0.6 0.6 0.08 3.6 0.078 0.044 0.924 0.885 0.177 0.918 0.887 0.206
0.6 1.0 0.05 3.6 0.081 0.058 0.977 0.970 0.388 0.972 0.974 0.435
0.6 1.0 0.08 3.6 0.080 0.050 0.946 0.935 0.380 0.960 0.945 0.451
0.6 1.5 0.05 3.6 0.087 0.062 0.982 0.981 0.556 0.982 0.985 0.590
0.6 1.5 0.08 3.6 0.080 0.056 0.972 0.972 0.597 0.975 0.973 0.622
0.6 4.0 0.05 3.5 0.080 0.064 0.995 0.995 0.837 0.994 0.993 0.855
0.6 4.0 0.08 3.6 0.082 0.064 0.988 0.991 0.850 0.990 0.990 0.857

These results are for the case of having 20% of probes as a internal control probes (needed for the REX approach) and 10% of probes as a true altered probes. The results are given for different scenarios between probe variability (σβ), probe-test variability (σγ) and within-probe variability (σε). The column x¯alt indicates the mean number of simulated altered probes.