# Talk:68–95–99.7 rule

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WikiProject Mathematics (Rated Start-class, Low-importance)
This article is within the scope of WikiProject Mathematics, a collaborative effort to improve the coverage of Mathematics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
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Field: Probability and statistics

## three-sigma rule is a more elegant name

From my stat courses I rarely heard professors saying "68–95–99.7 rule". Don't you think "three-sigma rule" is a more elegant title for this page? 128.97.77.169 (talk) 02:25, 1 August 2014 (UTC)

## Merging or keeping as own article

Shouldn't this just redirect to normal distribution? Richard001 06:30, 11 April 2007 (UTC)

No. This page gives a practical dervied result of a normal distribution. Its also much more directly useful to most people than the math-heavy normal distribution article (which is linked to). --Nantonos (talk) 13:16, 29 June 2008 (UTC)
However, the only useful information are the percentages, which you can work out anyway from the Normal Distribution article. It's pretty misleading to wrap it up in an 'empirical rule', since it's not *empirical* by that definition. Darktachyon (talk) 09:24, 22 October 2010 (UTC)

It seems like the mention of rejecting the normality data based on a"6σ" event occurring more than once in 1.5 million years is subject to the Gambler's fallacy. The probability doesn't determine how often it happens over time, but rather how likely the event is to occur for each specific instance, which in the case of the example, is a day. The expected time between events may be 1.5 million years, but this says nothing about time between individual events. You can't outright reject a coin's fairness if it lands on heads ten times in a row, so likewise you can't really reject the normality of the data based on only a few samples, regardless of the magnitude of probabilities involved. Of course this doesn't rule out that the initial prediction is incorrect, but it requires more samples than 2 or 3 to make a statistically significant conclusion. --Styrofoamboots (talk) 05:06, 6 May 2009 (UTC)

## "A description and illustration using Java Applets by Balasubramanian Narasimhan"

Appears to be an error in the example used in "A description and illustration using Java Applets by Balasubramanian Narasimhan"

Exerpt:
An Example
Let us apply the Empirical Rule to Example 1.17 from Moore and McCabe.
The distribution of heights of American women aged 18 to 24 is approximately normally distributed with mean 65.5 inches and standard deviation 2.5 inches. From the above rule, it follows that
68% of these American women have heights between 65.5 - 2.5 and 65.5 + 2.5 inches, or between 63 and 68 inches,
95% of these American women have heights between 65.5 - 2(2.5) and 65.5 + 2(2.5) inches, or between 63 and 68 inches.

95% of these American women have heights between 65.5 - 2(2.5) and 65.5 + 2(2.5) inches, or between 60.5 and 70.5 inches.
--Hallbg (talk) 17:15, 21 July 2009 (UTC)

The demo linked to was reported earlier as not working, but it worked OK in Firefox 3.5.5 today for me. --Kay Dekker (talk) 21:14, 14 November 2009 (UTC)

## Why 68, 95, and 99.7

Where do the figures come from. What is the reasoning behind using these values? — Preceding unsigned comment added by 92.27.94.107 (talk) 10:32, 8 March 2012 (UTC)

Yeah, why not 69.2, or 96? Is this rule used to determine a std deviation, or does a std dev always follow this rule? Mang (talk) 04:04, 2 December 2012 (UTC)

## 3-smegma genius

If someone is claiming an IQ at the 3-sigma level, and you suspect or know it to be an empty boast, congratulate them on being 3-smegma. ;O) 78.144.76.100 (talk) 06:35, 13 August 2012 (UTC)

Lol. I wish you had a talk page so that I could give you the Wikpedia Good Humor barnstar, or create one if not yet extant. ;O) --FeralOink (talk) 09:56, 24 December 2012 (UTC)