Conformational indistinguishability. v(r) is plotted as a function of the relative uncertainty, r = e/N. The limiting threshold noise levels for ensembles N = 7–23 are given by ensemble identity, N, and are placed at x = {[(N − 3)2 + 4]1/2 − (N − 3)}/N, y = 2/[W × (W − 1)] which are the limiting relative noise levels and inverse of total number of conformational pairs, respectively. ○: 3-mer; □: 6-mer; ⋄: 9-mer; ▵: 12-mer; ▿: 15-mer; 7–23: Limiting errors for 7–23 mers.