People often tell us that we're more than three deviations away from normal. According to the curve, that means we're cooler than 98% of the population! Nerds do come out on top.
…but we’re more interested in Normal in the mathematical sense.
The normal curve looks like this. It’s the bell shaped graph that results when statisticians
plot data with a… normal distribution. Basically, the total area under the curve
This area is divided up into standard deviations… the areas to the left and right of the middle
of the curve…
…and it also happens to be the average of the data.
Take male height for example.
The average height of an adult male is seventy inches, or five feet ten inches, with a standard
deviation of four inches.
That means that sixty-eight point two percent of all males are within four inches of five
foot ten. These guys are considered “normal.”
Unfortunately for Gene, at six foot five, he falls two deviations away from the average.
The second deviation from either side of the midpoint makes up twenty seven point three
percent of the area under the curve.
In Gene’s case, he falls into the twenty seven point three percent of the population
who is either shorter than five six or taller than six two.
So he has to shop at one of these. At least Gene still falls into the ninety
five point five percent of the population within two standard deviations of the average.
But what about that other four point five percent? Who are those guys?
Anyone shorter than five two or taller than six six will land three standard deviations
from the average.
These guys make up four point two percent of the population.
That means that ninety-nine point eight percent of men stand within three standard deviations
of five feet ten inches tall. So Gene may not fall within one deviation
for height… but what about his other features?
Maybe nose length? Whoa, nope.
How about hair color? Sorry, don’t think Gene will be with the majority on that one
Hey, wait a minute. With that big head of his he’s got to have a decent IQ, right?
Let’s see where the Green Bean falls.
The average IQ score is one hundred.
The standard deviation is fifteen points, so does Gene fall within one standard deviation?
Sweet! Gene, with his barely above average IQ…
…can join sixty eight point two percent of the population within one standard deviation
of the average.
Congratulations, average pants!