There actually has been a formal double blind study on whether jumping out of planes with parachutes save lives. The result found no life saving correlation, bu

There actually has been a formal double blind study on whether jumping out of planes with parachutes save lives. The result found no life saving correlation, but suffered from other experimental problems. Study did not get "off the ground" so to speak due to lack of participants agreeing to participate in the at height part due to reluctance to accept the risk of being in the placebo'd control group.