alt Hacker NewsOne of the more tractable examples here is the information what cell towers your cell phone is connected to. On it's own, it doesn't tell you that much.
But if you have this from 2-3 people, you can start inferring if they are meeting sporadically, meet a lot, possibly live together.
Or, if you add information about the services in the vicinity of cell towers, you can start deducing changes in a persons life. Suddenly the phone is moving more, to places with a doctor nearby, a gynecologist nearby, clothing stores, furniture stores, ... eventually a hospital. Start mixing in information about the websites they visit...
This incremental discovery of information about a person is surprisingly powerful depending on the data you have and hard to predict.
I agree with this completely. I feel like my phone is leaking so much sensitive information about me in so many ways. And it has access to my location, my communications, my finances. And it is hard to turn off. I can turn off my vacuum cleaner for months if I want. I can't turn off my phone or the computer in my car.
I guess that's why the vacuum doesn't worry me. The phone really does.