The much-vaunted hierarchy of evidence is regularly referred to by scientists and doctors as a central part of the scientific method. It is the purported gold standard by which we can arrive at the truth of something, and by which we can weigh different kinds of evidence, and determine which should be given more credence, and which should be given less. The hierarchy of evidence is often brought into debates by those pushing the vaccine, GMO and fluoride agendas as a way to prove that the “science” behind those agendas is sound. However, there is one rather colossal problem with invoking the hierarchy of evidence to prove your case, but before we get to that, let’s take define what the hierarchy of evidence is.
What is the Hierarchy of Evidence?
In a nutshell, the hierarchy of evidence, although different people and institutions construct it slightly differently, gives most weight to RCTs (Randomized Controlled Trials), then next to other kinds of controlled trials, then to other studies such as cohort and case-control studies, and lastly to expert opinion, case reports and anecdotal evidence. Wikipedia uses the writing of Greenhalgh to frame the hierarchy of evidence as follows: