The axes of the ERCC Dose Response plot are log (base 2), with the raw read counts for each ERCC transcript on the y-axis and the known relative concentration of the ERCC transcripts on the x-axis. In the plot, the points are color-coded—based on mapping quality—and there is also a line of best fit, the parameters (slope, y-intercept, and R‑squared value) of which are shown in tabular form to the right of the graph (N = the number of points (ERCC transcripts) included in the regression analysis). Ideally, the points all fall on a straight line. However, the raw counts and relative concentration should at least correlate with a high R-squared (e.g., ≥0.9) value. Although there are 92 transcripts in the ERCC mix, it is not expected that all 92 are detected. The number of transcripts detected depends on the sequencing depth.