Figure 1.
Phred quality value validity. The solid line corresponds to perfect agreement between observed and predicted, and the dotted lines indicate a deviation of ±5 (or roughly a factor of 3 in the corresponding error probabilities). Predicted quality values with no errors among the aligned bases are assigned observed quality value 60. Quality values 1, 2, 3, 46, 47, 48, and 50 are unused because the calibration procedure did not produce lookup table lines at these values.
