How reliable are these numbers? In particular, I'd like to see a precise definition of an active user. It seems odd to have such a sudden switch with no extern

How reliable are these numbers? In particular, I'd like to see a precise definition of an active user. It seems odd to have such a sudden switch with no external factors. To add 1.5M active users in a demographic in Feb and March and end up with just over 2M at the end of May seems fishy "When asked for comment, a Facebook spokesperson responded, 'Bear in mind that these tools gives out estimates, not real-time figures.'"