1. A radio frequency identification (RFID) system for monitoring a space, the system comprising: a controller connected to a plurality of RFID readers, the readers to detect data signals from a plurality of RFID tags carried by objects, the objects corresponding to one or more object categories; a database accessible by the controller, the database to record (1) times when data signals are received from tags in the plurality of RFID tags, and (2) the data contained in the data signals from the tags; and at least one processor to communicate with the controller, the at least one processor to: perform an inventory analysis of the objects based on a confidence probability curve; calculate in-store probabilities for the tags based on the confidence probability curve and at least some of the times when the data signals were received; sum the in-store probabilities; and when sales information is received, attempt to match a first RFID tag to the sales information based on a first data signal detected by at least one of the RFID readers.