This year's Christmas BMJ actually contained an RCT of parachute use when falling out of aeroplanes. It found no effect. It turns out that study design can als

This year's Christmas BMJ actually contained an RCT of parachute use when falling out of aeroplanes. It found no effect. It turns out that study design can also be a problem, even with 'gold standard' designs like the RCT... https://www.bmj.com/content/363/bmj.k5094 https://www.bmj.com/content/363/bmj.k5094