Range Rule of Thumb Formula

The Statistics range rule of thumb is used to decide if a value is unusual.  The easy way for me to remember the rule of thumb formula is by the distance.  If the distance is greater than or equal to 2 standard deviations away from the mean the event is unusual.

To formula for the minimum starts at + 2 standard deviations, the maximum starts at +2 standard deviations

If a number seems high or low do the test if it is a discrete probability distributions or binomial probability distributions problem.  The probability of an unusual event is between 5% to 0(repeating)1%.

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Last Modified on February 18, 2013 by Joseph Schumacher