Figure 2. Observed reads were mapped against known ERCC reference sequences, and read counts were compared against known amounts added in the spike-in control.

High correlations between samples (all Pearson correlation coefficients > 0.998, all Spearman correlation coefficients > 0.992) and to known concentrations (all Pearson correlation coefficients > 0.88, all Spearman correlation coefficients > 0.9, see methods for details) indicate that the sequencing and mapping procedures are effective and reproducible across a variety of transcript lengths.