Wednesday, February 11, 2009

Variance and Standard Error

In addition to dispersion we can also measure distribution of data with variance and standard error.

The variance is found by subtracting each observation from the mean, squaring it, then summing them all together. Mathematically this is:

Variance = Sum(n-u)^2/N

were n is any observation, and u is the mean.

The Standard deviation is simply the square root of this number.

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