4 ms·

This is for Facebook's ad targeting. They want advertisers to be able to advertise to 21-24 year old women in California.

• jfengel 6y ago
  They can probably infer it as accurately as asking people. The inference isn't always accurate, but people don't always tell the truth, either.
  • ecnahc515 6y ago
    They can do both. Someone lying or their inference being wrong about their gender is yet another new data point.