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Standard Deviation

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I 'll be honest. Standard deviation is a more difficult concept than the others we 've covered. And unless you are writing for a specialized, professional audience, you 'll probably never use the words "standard deviation" in a story. But that doesn 't mean you should ignore this concept.

The standard deviation is kind of the "mean of the mean," and often can help you find the story behind the data. To understand this concept, it can help to learn about what statisticians call normal distribution of data.

A normal distribution of data means that most of the examples in a set of data are close to the "average," while relatively few examples tend to one extreme or the other.

Let 's say you are writing a story about nutrition. You …show more content…

In this way, looking at the standard deviation can help point you in the right direction when asking why information is the way it is.

The standard deviation can also help you evaluate the worth of all those so-called "studies" that seem to be released to the press everyday. A large standard deviation in a study that claims to show a relationship between eating Twinkies and shooting politicians, for example, might tip you off that the study 's claims aren 't all that trustworthy.

Of course, you 'll want to seek the advice of a trained statistician whenever you try to evaluate the worth of any scientific research. But if you know at least a little about standard deviation going in, that will make your talk with him or her much more productive.

Okay, because so many of you asked nicely...
Here is one formula for computing the standard deviation. A warning, this is for math geeks only! Writers and others seeking only a basic understanding of stats don 't need to read any more in this chapter. Remember, a decent calculator and stats program will calculate this for you...

Terms you 'll need to know x = one value in your set of data avg (x) = the mean (average) of all values x in your set of data n = the number of values x in your set of data

For each value x, subtract the overall avg (x) from x, then multiply that result by itself (otherwise known as determining the square of that value). Sum up all those squared values. Then divide that result by

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