Figure 4
From: Improved base-calling and quality scores for 454 sequencing based on a Hurdle Poisson model
Distribution of HPCall quality scores at HPLref3 overcall. The empirical cumulative distribution function of HPCall quality scores Q Sovercall assigned to bases associated with HPL 2, 3 and 4 for sequences with reference HPLref 3. The quality scores associated with HPL 2 and HPL 3 are generally large, whereas HPL 4 gives smaller quality scores. HPCall clearly indicates that overcalls are more likely in this situation, whereas this insight is not provided by the native 454 quality scores.