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
Ok, stats major here and I finally understood it like this:
We have 10 data points or numbers. These 10 numbers have an average. What we want to find out is how dispersed are those numbers from the average.
So we start taking each of those 10 numbers, and subtracting it from the average to get the distance between them.
So now that we have the distance of each of the 10 points from the average, let’s sum up all the distance. Now if you divide the that total distance by the number of points there are, you therefore get the average distance of the data set from the average.
ADDITIONAL: Now of course, stats being stats, there are numerous nuisances – each one of those 10 numbers is either above or below the average so the distances will be negative and positive numbers. But like in real life, distance can’t be negative… So we square all the numbers and then take their square root to remove the negative sign. Then there also the degrees of freedom involved …but that’s for another day.
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