How Facebook's Safety Check Works
Saturday, November 14, 2015 at 8:33AM
Todd Hoff in Example

I noticed on Facebook during this horrible tragedy in Paris that there was some worry because not everyone had checked in using Safety Check (video). So I thought people might want to know a little more about how Safety Check works.

If a friend or family member hasn't checked-in yet it doesn't mean anything bad has happened to them. Please keep that in mind. Safety Check is a good system, but not a perfect system, so keep your hopes up.

This is a really short version, there's a longer article if you are interested.

When is Safety Check Triggered?

How Does Safety Check Work?

How is the impacted area selected?

How do you build the pool of people impacted by a disaster in a certain area?

The solution leveraged the shape of the social graph and its properties:

In Practice this Solution Was Very Effective

On HackerNews

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