I was lucky enough to attend the announcement made in 2012 of the discovery of the Higgs Boson. It consisted of a hour-long talk mostly about statistics, and how the particle physics community can only claim a discovery when their data has achieved a 5σ confidence level. This represents a 1 in 3.5 million probability of the result occurring by chance. I started thinking: how much chemistry is asserted at that level of confidence? Today, I read Steve Bachrach’s post on the structure of Citrinalin B and how “use of Goodman’s DP4 method indicates a 100% probability that the structure of citrinalin B is (the structure below)”. Wow, that is even higher than the physicists. Of course, 100% has been obtained by rounding 99.7 (3σ is 99.73%) or whatever (this is one number that should never be so rounded!). 
But there was one aspect of this that I did want to have a confidence level for; the absolute configuration of citrinalin B. Reading the article Steve quotes[cite]10.1038/nature13273[/cite], one sees this aspect is attributed to ref 5[cite]10.1021/jo051499o[/cite], dating from 2005. There the configuration was assigned on the basis of “comparison of the electronic circular dichroism (ECD) spectra for 1 and 2 with those of known spirooxiindole alkaloids“. However, this method can fail[cite]10.1002/chem.201101129[/cite]. Also, one finds “comparison of the vibrational circular dichroism (VCD) spectra of 1 with those of model compounds“[cite]10.1021/jo051499o[/cite]. Nowadays, one would say that there is no need for model compounds, why not measure and compute the VCD of the actual compound? Even a determination using the Flack crystallographic method can occasionally be wrong![cite]10.1021/jo401316a[/cite]. Which leads to asking what typical confidence levels might be for these three techniques, and indeed whether improving instrumentation means that the confidence level gets higher with time. OK, I am going to guess these.