What is a Quality Score in Sequencing?

最后发布时间:2022-07-28 14:56:13 浏览量:

Q Score Definition

The sequencing quality score of a given base, Q, is defined by the following equation:

Q = -10log10(e)

where e is the estimated probability of the base call being wrong.

Higher Q scores indicate a smaller probability of error.
Lower Q scores can result in a significant portion of the reads being unusable. They may also lead to increased false-positive variant calls, resulting in inaccurate conclusions.

A quality score of 20 (Q20) represents an error rate of 1 in 100 (meaning every 100 bp sequencing read may contain an error), with a corresponding call accuracy of 99%.

When sequencing quality reaches Q30, virtually all of the reads will be perfect, with no errors or ambiguities. This is why Q30 is considered a benchmark for quality in next-generation sequencing (NGS).

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