The headline says that 9 out of 10 people use social networks. The reality of the article is the claim that 90% of the over 15's who use the internet use social networks. Not quite the same thing.
The headline you’ll have seen recently says that e-books are outselling physical books on Amazon for the first time. In fact, e-books are outselling hard cover books for the first time. Paperback sales far exceed e-book sales which across the whole book sector only accounts for 3% of sales. Not quite the revolution that was suggested.
The headline is not to forget the importance of looking beneath the headline and of truly understanding the numbers. On the other hand, it also shows the importance of a headline and how easy it is to make people believe.