“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.”
https://www.bmj.com/content/327/7429/1459.short?fbclid=IwAR0hTt57o-yFS61aJE-IGCpKSPaDs--rdrPlbiby_wBCF1czpAWDaCcAEcM_aem_ATiWMtvZxiSzw8pj9CX271gyDByuMHTOKwQskBcCXx9aZOj1IPusHJ_z79olcRiFlhE