For comparison, we repeated the fits for these three noise levels for the original parameterization of the NK model, i.e., ref = 0. These results are also summarized in Table , Trials 4-6, row 15. At each noise level, the parameter and retention factor predictions were significantly worse than the proposed parameterization at ref = 0.3. Note that for the low and high noise levels, the maximum % error in the isocratic k estimate using the original parameterization was over 1000 % (Table , row 16, Trials 5 and 6).