Suppose a measurement is made on some physical characteristic whose value is known, and let x denote the resulting measurement error. for an unbiased measuring instrument or technique, the mean value of x is 0. assume that any particular measurement error is normally distributed with variance s2. let x1, . . xn be a random sample of measurement errors.

a. obtain the method of moments estimator of s2.

b. obtain the maximum likelihood estimator of s2.