The Syrian hamster has an average life span of two to three years. Although uncommon, these hamsters can sometimes live up to five years. A hamster's life span can be extended to a degree by providing it with a clean environment and fresh food daily. Continue Reading.
and substituting the estimate for gives. which is an unbiased estimator of the variance of the mean in terms of the observed sample variance and known quantities. Note that, if the autocorrelations are identically zero, this expression reduces to the well-known result for the variance of the mean for independent data.
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.