Variability of NSSDA Estimations

Abstract

Using a statistical simulation process the variability of National standard for spatial data accuracy (NSSDA) estimations are analyzed according to sample size. Simulation results show: (1) that the NSSDA positional accuracy estimation has a variability of 11% when using the minimum recommended sample size of 20 points; and (2) that the use of samples of 100 points is needed in order to reach an effective confidence level of 95%. The NSSDA is a methodology of shared risk between users and producers when accuracy is “as expected,” but for other cases the relation is altered. As simulation results demonstrated, this change is depicted by means of a family of acceptance curves that can be used by users to determine the sample size for limiting their acceptance risk, but also by producers to analyze their rejection risk.