<p>(<b>A</b>) Quantile-quantile (q-q) plots under NQS filtering show good fit of the probability model to the observed distribution of errors. Since the probability model is discrete, p values are projected onto a uniform distribution, and the distribution of projected p values is compared with the expected null distribution. See <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002417#s4" target="_blank">Materials and Methods</a> section for details. (<b>B</b>) In contrast, q-q plots under no filtering show that no filtering skews the calibration of the probability model used by <i>V-Phaser</i>. Q-q plots of models based on subsets of the reads demonstrate that this effect becomes more pronounced with increasing coverage (see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1002417#pcbi.1002417.s001" target="_blank">Figure S1</a>). Q-q plots are scaled to fit curve, so y = x line is not at a 45 degree angle.</p
