First of all, an example; mean age of the children in a test is 12.93, with a standard deviation of .76.
Now, maybe I am just over thinking this, but everything I Google gives me this big convoluted explanation of what standard deviation is without addressing the kiddy pool I’m standing in.
Edit: you guys have been fantastic! This has all helped tremendously, if I could hug you all I would.
In: Mathematics
It’s a measure of how tightly clumped your date is around the mean. If your data has low standard deviation then all your datapoints are tightly clumped around your mean. If your data has high standard deviation then your datapoints are very spread out, with the mean somewhere in the middle.
Standard deviation is simply a commonly accepted way of measuring this spread. You calculate it as follows
– take every datapoint and work out how far from the mean it is, the simplest way to do that is simply minus the mean from it which will give you the distance if the datapoint is bigger than the mean and minus the distance if the datapoint is smaller than the mean
– square them all to make them all positive so they’re easier to compare (don’t worry we’ll undo this later)
– work out the average (ie the mean) of those answers
– take the square root of that average (to undo the fact that you squared them all earlier)
and that’s your standard deviation
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