Rando Mth

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Variance is the measure of spread Read as: the variance (sigma squared) is equal to the squared mean minus the mean squared

The mean is calculated via the sum of all the variables in an array, This is just saying, starting from 1 continue until n and execute the logic to the right of the sum symbol, that weird E looking thing. So as it iters it’s adding the previous indexed logic to the current, etc. It’s simply a for loop if you’re a programmer!

Ending this, we calculate the squared mean by simply squaring x, You probably have noticed that the line above the variable means, well, the mean and the squared part tells us how the array was summed.

The standard deviation is the root of variance. As we will see in the future, the standard deviation is often used in calculations where we want to quantify how “surprising” a particular observation is.

The reason we do a squared difference is bc when we square the distances we get a quantity that increases whenever the data set becomes more spread out AND to make the distances non-negative, otherwise the difference would always be 0, no matter how spread out the distribution is!