Phred scores (also known as Q scores) are used to assess sequencing accuracy. The higher the Q score, the more accurate the data.
| Phred Quality Score | Probability of Incorrect Base Calls | Base Call Accuracy |
|---|---|---|
| 10 | 1 in 10 | 90% |
| 20 | 1 in 100 | 99% |
| 30 | 1 in 1,000 | 99.9% |
| 40 | 1 in 10,000 | 99.99% |
| 50* | 1 in 100,000 | 99.999% |
At this point (2024) many of the DTOL assemblies are somewhere around the Q40/Q50 metric.
Reference:
https://www.illumina.com/documents/products/technotes/technote_Q-Scores.pdf