Figure 2

Determination of detection above background. To determine if a given probe signal is detected above background, the PM intensity is compared to a distribution of background probes with the same G/C content. A p value is calculated representing the probability that the signal intensity is part of the null distribution. Probes with DABG p values of less than 0.05 are considered to be detected above background. For this study, the mismatch probes from PSRs supported solely by GenScan Suboptimal predictions were used to create the null distributions. (a) Diagram depicting the comparison of background signal to PM signal. PM signal intensities at the 95% of background probes with the same GC content are given a p value of 0.05. (b) ROC curve of the median DABG p value from all 48 samples. The area under the curve (AUC) is used as a measure of ability of the metric to differentiate between expressed and non-expressed sequences. The sensitivity and specificity values are shown for a DABG p value cutoff of 0.05. (c) Table of the median sensitivity and specificity values for each tissue using a DABG p value cutoff of 0.05.