1. A method comprising: receiving, at one or more processors and for each of multiple network devices distributed throughout a geographic region, at least one measured performance characteristic value corresponding to that network device; identifying, by the one or more processors, a first of the multiple network devices and a subset of the remaining multiple network devices within a calculated geographic range of the first network device; and classifying, by the one or more processors, the identified network devices as a problem device grouping based on collective evaluation of the received values corresponding to the identified network devices.