Systems and methods including mobile devices determining their locations using location determination units, such as GPS receivers. A computing device generates a statistical measurement of location pattern changes in relation to a predetermined region for a predetermined period of time. The measurement is generated from a difference between responses of exposed mobile devices and responses of non-exposed mobile devices, which devices are selected based on a cluster analysis to match the distributions of the exposed mobile devices and the non-exposed mobile devices in an attribute space. Each response of a mobile device can be computed based on applying, at a time instance, an anti-symmetric weight function having an exponential distribution to a time series of visitation measurements to generate a response corresponding to the time instance, and summing the responses corresponding to time instances falling within the predetermined period of time as the response of the mobile device.