1. A method for estimating a population of Radio Frequency Identification (RFID) sensors in an area based upon responses during an interrogation frame processed by a processing system in a transceiver system receiving the responses comprising: receiving responses from RFID sensors during a plurality of time slots of a receiving frame; determining a contention resolution of each of the plurality of time slots; determining a probability state for each of a plurality of population estimates based upon the contention resolution for each of the plurality of time slots; where the probability state of a population estimate is a confidence in the population estimate based upon the contention resolution observed in the plurality of time slots of a particular receiving frame; estimating a probability for each of the plurality of population estimates based on the probability state; selecting one of the plurality of population estimates as a population based upon the estimated probability of the selected one of the plurality of population estimates meeting a predetermined criteria.