Quality Values for DNA Sequencing

Numerical Quality Scores

Table Explaining the Quality values assigned to each base of a sequencing reaction analyzed by the program Sequencing Analysis. The values are also commonly known as PHRED values.

table of dna sequencing quality values












Graphical Quality Scores

The Quality values are represented as vertical bars above each base with a positive correlation between the height of the bar and the quality of the base assignment.  Blue bars represent values of >/= 20, and yellow bars are values <20, but =/>15.  The red bars represent values < 15, and an N is <10.  The electropherogram below has examples of all 4 categories for the Quality Value scores.