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Revision as of 16:10, 23 February 2012
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= Overview of the <code>indelDiscordance</code> function of <code>bamUtil</code> =
= Overview of the <code>indelDiscordance</code> function of <code>bamUtil</code> =
The <code>indelDiscordance</code> option on the [[bamUtil]] looks at discordance at sites on the male X chromosome.
The <code>indelDiscordance</code> option on the [[bamUtil]] looks at insertion/deletion discordance.
By default it looks only at the non-pseudoautosomal region of the X-Chromosome.
== ASSUMPTIONS/RESTRICTIONS ==
== ASSUMPTIONS/RESTRICTIONS ==
* Only works on one chromosome at a time
* Repeats are single-base only
** An unrepeated base has repeat count = 0 ('A')
** A base repeated once has repeat count = 1 ('AA')
* Skips reference positions with base 'N'
== What is a Discordance ==
A position is considered to have a Deletion Discordance if at least 1 read has a match/mismatch AND at least 1 read has a deletion AND there are at least the "minimum depth" reads at this position.
A position is considered to have an Insertion Discordance if at least 1 read has an insertion following this position AND at least 1 read does not AND there are at least the "minimum depth" reads at this position.
== Error Rate Algorithm ==
The weighted average error rate, weighted average deletion error rate, and weighted average insertion error rate are calculated for each repeat count.
The error rate is weighted by the depth, so the discordant counts are
For each Repeat Count in the File
For each Depth at this Repeat Count in the file
if (depth > MaxAllowedDepth)
skip calculating error rate for this depth
else
// Note: numDiscordant is not equivalent to numDeleteDiscordant + numInsertDiscordant since a position could have both types of discordants
numDiscordant = number of discordant positions with this repeat count and depth
numDeleteDiscordant = number of deletion discordant positions with this repeat count and depth
numInsertDiscordant = number of insertion discordant positions with this repeat count and depth
count = number of positions with this repeat count and depth
<math>errorRate = 1 - (\tfrac{numDiscordant}{count})^{({\tfrac{1}{depth}})}</math>
sumErrorRates += errorRate * count * (depth-1)
numErrorRates += count * (depth-1)
Repeat Count Weighted Error Rate = sumErrorRates/numErrorRates
