MULTIPLE METER DETECTION AND PROCESSING USING MOTION DATA

Systems and methods are disclosed for identifying portable devices carried by the same person. An example system includes receiving media exposure data over a data network from at least one of a plurality of portable computing devices, motion strings to be received over the data network respectively from each of the plurality of portable computing devices, each of the strings including a successive binary representation of motion over a first period of time, the first period of time divided into a plurality of sub-periods of time, and comparing the motion strings to determine if at least two motion strings match within a predetermined threshold, and identify the devices that produced matching motion strings as being physically carried by a same person.