A lot of geolocation data on the market is anonymized, following medium-lived unique IDs that aren't able to be mapped to other identifiers. The problem with that is that if you have precise locations, or enough samples that you can apply statistics to find precise locations, in many cases you can de-anonymize the IDs. You can purchase address and resident listings from a number of different data vendors, and by checking where the device returns to at night you can figure its home address. Then if you find information on the residents (work locations, schools, etc.), you see if said device goes where each resident of the home address is likely to go, and you now have a pretty good idea of exactly who the device belongs to.