1. An authorized user authentication method, comprising: accessing data from an authorized user; using the data to create a first characteristic probability distribution representation indicative of the authorized user; accessing situation data from the authorized user during a situation; using the situation data to create a situation characteristic probability distribution representation indicative of the authorized user in a situation; accessing new data from a purported authorized user; comparing the new data of the purported authorized user to the first characteristic probability distribution representation for the authorized user; determining a probability that the purported authorized user is the authorized user based on the comparing; comparing the new data of the purported authorized user to the situation characteristic probability distribution representation for the authorized user; and determining a probability that the purported authorized user is in the situation based on the comparing.