Scatter plots of 5'ss scores of competitive and tandem donors (cf. notation of Figure 4). The upper panel shows the individual and mean scores (the latter is marked by solid/dashed lines); the lower panel compares on the left-hand side the cumulative score distribution of PΔ4 and dΔ4 splice sites with constitutive 5'ss and dΨ4 (pseudo distal 5'ss, in black), and on the right-hand side pΔ4 and DΔ4 splice variants with pΨ4 and 5'ss (pseudo proximal 5'ss, in black). The threshold at which the curves intersect (S*) marks the accuracy (A) at which sets can be distinguished with equal classification errors on major and minor splice variants. A(S*) ≈ 78% for PΔ4 versus dΔ4 (PΔ4/dΔ4) and A(S*) ≈ 92% for pΔ4/DΔ4, and A(S*) ≈ 95% for dΨ4/5'ss and A(S*) ≈ 99% for 5'ss/pΨ4. In the bottom, tables show the number of exons of each type above and below S*; ordered table entries are: TP, FP, TN, and FN (on white background).