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In statistics, the 68–95–99.7 rule, also known as the empirical rule, and sometimes abbreviated 3sr, is a shorthand used to remember the percentage of values that lie within an interval estimate in a normal distribution: approximately 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean, respectively.
About 68% of values drawn from a normal distribution are within one standard deviation σ from the mean; about 95% of the values lie within two standard deviations; and about 99.7% are within three standard deviations. [6] This fact is known as the 68–95–99.7 (empirical) rule, or the 3-sigma rule.
The approximate value of this number is 1.96, meaning that 95% of the area under a normal curve lies within approximately 1.96 standard deviations of the mean. Because of the central limit theorem, this number is used in the construction of approximate 95% confidence intervals. Its ubiquity is due to the arbitrary but common convention of using ...
as for "three sigma rule", idk, this sounds as if it was a rule dealing with a 3-sigma case, while "68-95-99.7" is actually a list of cases of n sigma, with a modest n=1..3. The page title actually helped me remember "68-95-99.7" by now, but as 4 or 5 sigma also occur in everyday considerations, I keep having to look it up anyway.
English: This histogram demonstrates the empirical rule, also known as the 68–95–99.7 rule. Note that the areas of histogram bars are not proportional to the stated probabilities, unless by an incredible coincidence.
It states that roughly 80% of the effects come from 20% of the causes, and is thus also known as the 80/20 rule. [2] In business, the 80/20 rule says that 80% of your business comes from just 20% of your customers. [3] In software engineering, it is often said that 80% of the errors are caused by just 20% of the bugs.
Hamas publicly endorsed the 2011 Sunni Muslim street uprising against Assad's rule and vacated its Damascus headquarters in 2012, a move that angered Iran, an ally of both Assad and the ...
Precise values of are given by the quantile function of the normal distribution (which the 68–95–99.7 rule approximates). Note that is undefined for | ...