During World War I, British soldiers started out wearing brown caps. And dying of head injuries. So they switched to metal helmets. Makes sense, right? Then they noticed the number of soldiers with head injuries was actually increasing. It would be easy to conclude that helmets weren’t helping, right? Not so fast. More head injuries were being reported because more soldiers were surviving those injuries. When someone had died, it was recorded as a fatality, not a head injury. The moral? When you look at the numbers, be sure you understand what they’re really saying.