Calibration of coin validation apparatus

Coin validation apparatus comprises a coin chute including means for deriving from a coin passing through the chute, a set of values related to one or more parameters of the coin, memory means for storing the respective sets of values for a multiplicity of coins representing different coin types of a coin set, and means for analysing the respective sets comprising means for statistically classifying the coins of each coin type so as to provide a statistical mean and variance value for selected values, means for comparing the statistical values for the respective coin types in order to locate statistical values which can be used to differentiate the respective coin types, means for estimating relative weightings for such differentiating values for determining their relative importance in differentiating coin types, and means for storing in said memory means such differentiating statistical values for future use in allocating individual coins to a coin type. Thus, one or more features is selected which provide the greatest distinction for those classes of coins which are least separated. The parameters employed may be the sound emitted when the coin strikes an anvil, and weight.