Earlier quoted context omitted.
> It sounds very strange that the death spike is "over" 3 sigma, which should mean over 3 standard deviations, which is really unbelievable, to me this looks like an artefact of some sort Why does the fact that it is larger than 3 standard deviations suggest to you that it must be an artifact? If the death rate is normally very stable then the standard deviation will be small, so it will be easy for any unusual incre…
I think the other thing that may be possible (just guessing, I'm not a statistician or actuarial) is that by using the term "3 sigma" I'm assuming they're modeling the data as a normal distribution. But these types of outlier events often follow power laws, such that you get "fat tails" when looking at a bell curve.
variance and standard deviation don't only apply to normal distributions. and "sigma" is the symbol normally used for variance regardless of the underlying distribution.
> I'm assuming
sigh.