|
Results of the simulation study: Differences between the p-values of the original two-part test and the two-part permutation test for data sets with small p-values (i.e. p-value of the original test ≤ 0.1), a positive difference means that the two-part permutation test has a smaller p-value than the original test; p1 and p2 are the probabilities for zero values and the positive values in group 1 are shifted by μ; 5,000 data sets with n1 = n2 = 10 were generated for each configuration |
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| Configuration |
Number of data sets |
Mean difference (± SD) |
Median difference |
Quartiles of the difference |
|
|
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| p1 = p2 = 0, μ = 2.5 |
4538 |
0.0118 (± 0.0145) |
0.0057 |
0.0013, 0.0161 |
| p1 = p2 = 0.3, μ = 2.5 |
4038 |
0.0008 (± 0.0069) |
0.0020 |
0.0008, 0.0033 |
| p1 = 0.4, p2 = 0.2, μ = 2.5 |
4346 |
0.0010 (± 0.0059) |
0.0019 |
0.0008, 0.0033 |
| p1 = 0.2, p2 = 0.4, μ = 2.5 |
4270 |
0.0011 (± 0.0056) |
0.0018 |
0.0006, 0.0030 |
| p1 = 0, p2 = 0.3, μ = 2.5 |
4883 |
0.0039 (± 0.0055) |
0.0020 |
0.0005, 0.0051 |
| p1 = 0.3, p2 = 0, μ = 2.5 |
4893 |
0.0040 (± 0.0053) |
0.0022 |
0.0007, 0.0049 |
| p1 = 0, p2 = 0.4, μ = 0 |
3427 |
-0.0033 (± 0.0119) |
0.0006 |
-0.0092, 0.0029 |
| cutoff value = 0.5, μ = 2.5 |
4621 |
0.0059 (± 0.0081) |
0.0034 |
0.0009, 0.0072 |
| cutoff value = 1, μ = 2.5 |
4860 |
0.0017 (± 0.0052) |
0.0013 |
0.0003, 0.0032 |
Neuhäuser et al. BMC Bioinformatics 2005 6:35 doi:10.1186/1471-2105-6-35 |
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