To date, there have been no studies comparing parametric and nonparametric Item Characteristic Curve (ICC) estimation methods on the effectiveness of Person-Fit Statistics (PFS). The primary aim of this study was to determine if the use of ICCs estimated by nonparametric methods would increase the accuracy of item response theory-based PFS for small sample sizes. Using three recognized PFS ("l[subscript z]", "ECI2[subscript z]", and "ECI4[subscript z]"), four estimation methods were compared: two parametric methods (the two-parameter logistic model and three-parameter logistic model) and two nonparametric methods (Nadaraya-Watson's regression and the local logistic regression). Finally, matrices of 100- and 1,000-answer vectors were generated for this Monte Carlo study. For both large and small sample sizes, the accuracy of the PFS was greater when used with the parametric models. (Contains 4 tables and 1 note.)