cfe-lab / cfe-lab/MiCall

minimum_q_delta is taking the difference on a log scale

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question
Dominant language
Python
Stars
21
Forks
11
Avg merge
12h 5m
Merged PRs (30d)
24

Description

I've been writing up some details of this pipeline for a review paper that Chanson and I are revising for a journal, and I just realized that when sam2aln.pyis resolving discordant bases while merging reads, it is taking the arithmetic differences of their respective quality scores. However, quality scores are a log-transformation of estimated error probabilities, which means that a difference of Q1-Q2=5 means something completely different for Q1=15, Q2=10 (-0.068) than it does for Q1=40, Q2=35 (-0.00022).

I don't think this is going to make a big difference, but I just thought I'd say something :)

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Research direction

Start by reading sam2aln.py and locate how minimum_q_delta is applied while resolving discordant bases during read merging. Confirm how quality scores are compared and determine the intended behavior from their error-probability interpretation. Done should mean the comparison is consistent with the documented quality-score semantics, with relevant behavior verified by the available tests.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
bioinformatics
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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