Allele-specific rank sum test of REF versus ALT base quality scores (AS_BaseQRankSum)
This variant-level annotation compares the base qualities of the data supporting the reference allele with those supporting each alternate allele. To be clear, it does so separately for each alternate allele.
The ideal result is a value close to zero, which indicates there is little to no difference. A negative value indicates that the bases supporting the alternate allele have lower quality scores than those supporting the reference allele. Conversely, a positive value indicates that the bases supporting the alternate allele have higher quality scores than those supporting the reference allele. Finding a statistically significant difference either way suggests that the sequencing process may have been biased or affected by an artifact.
The value output for this annotation is the u-based z-approximation from the Mann-Whitney-Wilcoxon Rank Sum Test for base qualities (bases supporting REF vs. bases supporting ALT). See the method document on statistical tests for a more detailed explanation of the ranksum test.
GATK version 18.104.22.168 built at Wed, 30 Jan 2019 10:21:04 +0530.