1. A method of estimating demographic information associated with a user of a mobile device while preserving the privacy of the user based at least in part on a location estimate of the mobile device of the user, the method comprising: (a) receiving an estimated geographical location of the mobile device of the user; (b) receiving a time at which the mobile device was at the estimated geographical location; (c) providing a set of substitute identifiers for a corresponding set of at least one geographical area; (d) assigning one of the set of substitute identifiers for the geographical area corresponding to the geographical location of the mobile device; (e) assigning a substitute identifier for the time at which the mobile device was at the estimated geographical location; (f) providing an association between the substitute identifiers for geographical areas and demographic information corresponding to the substituted geographical area; and (g) estimating demographic information associated with the user of the mobile device based on the assigned substitute identifiers and based on the demographic information associated with the provided set of substitute identifiers.