For those that don't get it this is survivorship bias.

During World War 2 they were attempting to figure out how to better equip the planes they had to survive. A certain statistician by the name of Wald figured out that the holes in the planes that they could track weren't that important because those were the planes that returned. Instead it was safer to assume that everywhere else needed better protection, as the planes that received damage in those areas weren't returning.

Sorry if I ruined the funny, but I saw the downvotes and was concerned.