I am planing to use interpolation method using spatial analyst tool and I found several methods like spline NN and kriging. I know I can do interpolation using geostatistical analyst but some interpolation methods do not available in geostatistical analyst like spline and NN, although the errors measurement can be obtained from geostatistical analyst. My question is how to get error results such as root mean square errors and both observed and predicted data of interpolation model using Spatial Analyst in ArcMap?