1. A method of operating a money validation system having at least two sensors and a processing and control circuit, comprising: defining an activity vector originating at the zero electrical activity point and terminating at an idle operating point for the system; sensing data with each sensor representative of at least two characteristics of each of a plurality of genuine money items; combining the sensed data into a plurality of acceptance vectors; mapping the acceptance vectors onto a coordinate system; defining a mean vector having its origin at the idle operating point and terminating at the center of the mapped region; defining a tolerance value for the mean vector; generating an acceptance region based on the tolerance value and the mean vector; sensing an inserted item and generating data representative of said at least two characteristics; converting the generated data of the inserted item into a test vector; comparing the test vector to the acceptance region; and accepting the item as a genuine item if the test vector falls within the acceptance region.