In this paper, some of the properties of non-parametric estimation of the expectation of g(X) (any function of X), by using a Judgment Post-stratification Sample (JPS), are discussed. A class of estimators (including the standard JPS estimator and a JPS estimator proposed by Frey and Feeman (2012, Comput. Stat. Data An.)) is considered. The paper provides mean and variance of the members of this class, and examines their consistency and asymptotic distribution. Specifically, the results are for the estimation of population mean, population variance and CDF. We show that any estimators of the class may be less efficient than Simple Random Sampling (SRS) estimator for small sample sizes. We prove that the relative efficiency of some estimators in the class with respect to Balanced Ranked Set Sampling (BRSS) estimator tends to 1 as the sample size goes to infinity. Furthermore, the standard JPS mean estimator and, Frey and Feeman JPS mean estimator are specifically studied and we show that two estimator have the same asymptotic distribution. For the standard JPS mean estimator, in perfect ranking situations, optimum values of H (the ranking class size), for different sample sizes, are determined non-parametrically for populations that are not heavily skewed or thick tailed. We show that the standard JPS mean estimator may be more efficient than BRSS for large sample sizes, in situations in which we can use a larger class size for H in JPS set-up.