TWO WEEKS AGO, Facebook locked me out of my profile. My photos and friends are gone, my profile vanished without a trace.
We already know that if you use an online social network, you give up a serious slice of your privacy thanks to the omnivorous way companies like Google and Facebook gather your personal data. But new academic research offers a glimpse of what these companies may be learning about people who don’t use their massive web services. And it’s a bit scary.