RFID system components, such as readers and tags, communicate where the reader inventories a population of tags. The tags choose randomly one of a plurality of slots in response to each one of the values communicated by the reader and reply according to their chosen slot. The reader may initiate the inventorying by determining a Q-parameter value from a stored value and communicating the Q-parameter value to the tags. The reader may evaluate replies received from the tags in another plurality of tags, determine a second value from evaluating the second replies, and store the second value for future use.