The 6 Å model contains several unique residues that do not appear in any of the τ 2B models: three such residues in 181L, eight in 1LI2, one in 1O48, and eleven in 1BOZ. Apparently, these do not significantly improve the accuracy when compared to the τ 2B model construction, however. The most significant differences between these two algorithms are found in 1O48 and 1BOZ, where the number and identity of residues varies greatly. For example, for 1O48 the 6 Å model contains only one unique residue but the model constructed using τ 2B = 2.5 × 10 -4 E h includes 15 additional residues. This discrepancy manifests as a 2 kcal/mol difference in errors at the MBE(2) level, illustrating how the precise choice of residues can significantly impact the result, and furthermore demonstrating that larger models do not always lead to smaller errors.