1. A method of determining a measure of likelihood that a single designated identifier is shared by at least two wireless devices, the method comprising: determining a set of one or more reference points associated with any wireless device having a designated identifier, one or more of the reference points being at least one of (i) a geographic position at which signals from any of the wireless devices having the designated identifier were detected and (ii) another wireless device from which signals were also detected by a receiver within a selected period of time during which the signals from any of the wireless devices having the designated identifier were detected by the receiver; determining statistical information about at least one of (i) a temporal distribution of times of detection of signals of reference points of the set, (ii) a spatial distribution of the reference points, and (iii) a cardinality of the set or at least one subset of the reference points; and determining a measure of likelihood that the designated identifier is shared by at least two wireless devices based on the statistical information.