Variance

According to Wikipedia, "variance" means,

In probability theory and statistics, the variance of a random variable is a measure of its statistical dispersion, indicating how far from the expected value its values typically are. The variance of a real-valued random variable is its second central moment, and it also happens to be its second cumulant. The variance of a random variable is the square of its standard deviation.

If μ = E(X) is the expected value (mean) of the random variable X, then the variance is

That is, it is the expected value of the square of the deviation of X from its own mean. In plain language, it can be expressed as "The average of the square of the distance of each data point from the mean". It is thus the mean squared deviation. The variance of random variable X is typically designated as , , or simply σ².

Note that the above definition can be used for both discrete and continuous random variables.

Many distributions, such as the Cauchy distribution, do not have a variance because the relevant integral diverges. In particular, if a distribution does not have expected value, it does not have variance either. The converse is not true: there are distributions for which expected value exists, but variance does not.

In Cresskill, New Jersey, a variance is something you file for if you want to add on a porch, extend a porch, or do anything different than what the original builders had in mind. And the process takes months with unending paperwork. As a result, the contractors who are, at this very moment, fixing my bathrooms and rebuilding the front porch to specific specifications have informed me that they will be unable to build the deck in the backyard because the right folks hadn't filed a "variance" with the city of Cresskill.

I could be misspelling variance while making my point here. Still, while there are may be many different meanings to the word, it still means I won't be getting my deck out back. It looks like I'll be hanging out on my front porch now more than ever. Which, I should point out, is what I probably would've done anyway. I do love sitting on a covered front porch, drinking iced tea, and petting my dog (of course, now I simply MUST get a dog).