Posts Tagged ‘normal distribution’

Normal is not average

April 20, 2015

People on the internet today love to get offended and very often people get offended by someone calling something “normal”. Especially if this “normal” is somehow different from them. But often people simple misunderstand the words normal and average and use them as synonyms, which they aren’t. There is a very big difference between normal and average and I’ll try to make it clear here. Understanding that difference is the key to not get offended so easily by these words.

So, this is the normal (Gaussian) distribution or the so-called bell curve:

the normal distribution
The line in the middle, in the green area, represents the average. It’s the mean score – the sum of all scores divided by the number of scores. So you can have a group of things with an average of x, although none of the things actually is x. For example when we take the ages of a group of 10 friends: 21 21 22 23 23 25 25 25 26 29. The average age of this group of friends is 24, although none of them is actually 24. But that’s not their “normal” age. Everything in the 95,4%-range is considered normal, in the case of our group of friends an age between 19 and 29 would be “normal”. Many researchers use the more strict 99,7%-range when testing their hypothesis. So normal are 95,4% of all things, while the average is the mean of all things.

My point is – often people say normal, but mean average. Average doesn’t mean good, it just means average, the arithmetic mean. Normal is almost everything. Normal doesn’t mean good, it just means that something is not extraordinary different than other things.

This article describes the problem really good and simple in the context of child development.

Also hobo mama had a very good post on that topic again in the context of child development.

So my loved ones – I wish you uniqueness and less “normality” and “averageness”.

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