The randomized controlled trial (RCT) is often called the “gold standard of evidence” in medical research involving humans. In such an experiment, a random sorting leads to only some subjects getting the real intervention being tested.

The first known RCT took place in 1747, when Dr. James Lind, surgeon on the HMS Salisbury, staked out his place in history by giving some scurvy patients citrus fruits. At first, anyway. Then all the sailors got citrus, as it became obvious that scurvy was preventable through the inclusion in the diet of vitamin C via consumption of oranges, lemons and—of key importance to etymologists—limes, which led to all British sailors, and then all Brits in general, to become known as Limeys.

Skip ahead a quarter of a millennium to 2003, when the BMJ, formerly known by its spelled-out name of the British Medical Journal (and informally to some as the Limey Medical Journal), published an article entitled, “Parachute Use to Prevent Death and Major Trauma Related to Gravitational Challenge: Systematic Review of Randomised Controlled Trials.”

The write-up was a response to a long-held criticism of RCTs, namely, that you don't need them to make reasonable conclusions about certain effects of certain actions—such as jumping out of a plane without a parachute. Indeed, the 2003 BMJ paper's objective, “To determine whether parachutes are effective in preventing major trauma related to gravitational challenge,” met with a hard landing. “We were unable to identify any randomised controlled trials of parachute intervention,” the authors admitted.

They explained further: “As with many interventions intended to prevent ill health, the effectiveness of parachutes has not been subjected to rigorous evaluation by using randomised controlled trials. Advocates of evidence based medicine have criticised the adoption of interventions evaluated by using only observational data. We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.”

Which brings us to the Christmas issue of the BMJ, always stocked with unconventional scholarship. The 2018 edition took up the gauntlet thrown back in 2003—researchers from Harvard University, the University of Michigan and U.C.L.A. joined with skydivers to publish “Parachute Use to Prevent Death and Major Trauma When Jumping from Aircraft: Randomized Controlled Trial.”

The team enlisted and randomized 23 volunteers. Twelve participants wore parachutes while the other 11 donned backpacks that contained no parachutes. All 23 leapt from either a plane or a helicopter. The jumpers were assessed shortly after hitting the ground for death or major trauma, and most were reevaluated 30 days later.

The authors wrote, “We have performed the first randomized clinical trial evaluating the efficacy of parachutes for preventing death or major traumatic injury among individuals jumping from aircraft. Our groundbreaking study found no statistically significant difference in the primary outcome between the treatment and control arms.” Indeed, all members of both cohorts were fine.

The researchers further note, “A minor caveat to our findings is that the rate of the primary outcome was substantially lower in this study than was anticipated ... [subjects] could have been at lower risk of death or major trauma because they jumped from an average altitude of 0.6 m [just under 2 feet] on aircraft moving at an average of 0 km/h.” As the reader suspected, the aircraft were parked on the ground.

The researchers also said, “Opponents of evidence-based medicine have frequently argued that no one would perform a randomized trial of parachute use. We have shown this argument to be flawed, having conclusively shown that it is possible to randomize participants to jumping from an aircraft with versus without parachutes (albeit under limited and specific scenarios).”

By the way, no participants actually deployed their parachutes—if you throw around square yards of fabric and feet of strings, somebody could get hurt.