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Fundamentals of Statistics 1: Basic Concepts :: The Empirical Rule
The
standard deviation
is the way variability is often described. If the data we are working with are roughly bellshaped and symmetrical (looking like a normal distribution) then we can use the standard deviation to tell approximately how much of the data will cluster around the mean.
The so called
empirical rule
states that the bulk of the data cluster around the mean in a normal distribution. In fact:
68% of values fall within
±
1 standard deviation of the mean
95% fall within
±
2 standard deviations of the mean
99% fall within
±
3 standard deviations of the mean
It's called the empirical rule since experimenters have observed roughly these patterns from their data over and over again when they empirically collect data.
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December 4, 2017  joyce wrote:
thanks
December 4, 2017  joyce wrote:
thanks
April 21, 2015  Nita Wright wrote:
The empirical rule is confusing to me in a way because it is discussing the date we've collected and how it can be off by 13 plus or minus. It might seem silly but while understand where the variation comes from I find it disconcerting at the same time. I feel like data can change from the group we are working with but the results from those groups wouldn't necessarily change. Does that make any sense?
November 16, 2012  kenya wrote:
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