From the description: [...] (I was unable to find any further explanation of how they do that.)
From the description:
We’re inviting people to participate in a survey conducted by Carnegie Mellon University Delphi Research Center, and over a million people responded to this survey within the first two weeks.
[...]
Every day, a new sample of Facebook users over 18 years old within the United States are invited to participate in the survey. Facebook doesn’t receive, collect or store individual survey responses, and CMU doesn’t learn who took the survey.
(I was unable to find any further explanation of how they do that.)
From the description:
[...]
(I was unable to find any further explanation of how they do that.)