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7: Aggregation and Grouping > Understanding Statistical Functions

Understanding Statistical Functions

Statistics wasn't my best subject in school. Although I understood the relevance and importance of statistics, my brain just wasn't wired for it. Fortunately, now that I use these functions regularly in consulting and application development work, I no longer struggle with it, but I often need to jog my memory by looking at an example. This section explains these concepts in simple terms and provides some useful examples for those of us who don't think statistically.

The VAR() Function

This function returns the statistical variance for a range of values, that is, a value that indicates how “spread out” the values are in the range. The value returned by this function is actually the measure of how far the extreme low range or high range value is from the middle—or mean value of the range, weighted by the greatest concentration of similar values. For example, given the range of values on a number line, 2, 3, 4, 5, and 6, the number 4 is the mean—it's in the middle of the range. In this simple example, the variance of this range is 2 (from 4 to 2 and from 4 to 6 both have a difference of 2). This is very simple if you have a list of distinct, incremental values but it gets a little more complex as the values are less uniform.


  

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