What is the meaning of Samona? How popular is the baby name Samona? Learn the origin and popularity plus how to pronounce Samona
Variance. Variance (Ï 2) is a measure of the dispersion of a set of data points around their mean value. In other words, variance is a mathematical expectation of the average squared deviations from the mean. It is computed by finding the probability-weighted average of squared deviations from the expected value. Variance measures the variability from an average (volatility).
Consider first the case where the target is a constantâsay, the parameter âand denote the mean of the estimator as . The mean squared error can then be decomposed as. The mean squared error thus comprises the variance of the estimator and the squared bias. The two components can be associated with an estimatorâs precision (small variance) and its accuracy (small bias). If is an unbiased estimator of âthat is, if âthen the mean squared error is simply the variance of the estimator. By choosing an estimator that has minimum variance, you also choose an estimator that has minimum mean squared error among all unbiased estimators.