alt Hacker News> It's like "A study found that parachutes were no more effective than empty backpacks at protecting jumpers from aircraft."
Are you under the impression that we don't bother to empirically prove things that seem obvious, like the safety benefits of parachutes? You don't think parachute manufacturers test their designs and quantify their performance?
There are no randomized controlled trials that parachutes save lives.
This is repeatedly used as an example in the medical community about the limits of randomized controlled trials. This isn't some impression - your impression that such evidence exists is wrong.
There might be some parachute company tests about effective of velocity, etc., but there are no human trials.
Why? Because that would be unethical.