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Table 2 Comparing the type I error rate for the four different methods in the presence of 200 outliers

From: DiffVar: a new method for detecting differential variability with application to methylation in cancer and aging

 

Nominal P-value

Test method

0.001

0.01

0.05

0.1

Bartlett

0.01379

0.02601

0.06781

0.1179

F test

0.01467

0.02663

0.06767

0.1172

DiffVar (abs)

0.0009701

0.01006

0.05085

0.1019

DiffVar (sq)

0.0005373

0.008198

0.04880

0.1011

  1. Median type I error rates are reported for 1000 simulations with no differentially variable or differentially expressed features, but with 200 outliers incorporated in the data. The standard deviation with which the error rate is estimated ranges from approximately 0.0003 for rates near 0.001 to 0.003 for rates near 0.1 with the Bartlett and F test more variable than DiffVar at nominal p-values of 0.001 (sd approximately 0.002 compared to 0.0003) and 0.01 (sd approximately 0.0018 compared to 0.0010).