1. An occupant classification system for a vehicle, the system comprising: a plurality of sensors, each sensor configured to produce an output related to a characteristic of an occupant in a seat of the vehicle; and a controller configured to receive the output of each of the sensors and to perform a maximum likelihood ratio test to provide a signal indicative of the classification of the occupant, wherein the maximum likelihood ratio test incorporates the output of each individual sensor relating to the occupant, and further incorporates a mean and a covariance of each of a pair of data sets, wherein each data set is related to a specific class and includes the outputs of each of the sensors in response to a plurality of test cases.