第4章用样本推断总体-参数估计祥解.ppt

* 90 * * * 38 In this diagram, do the populations have equal or unequal variances? Unequal. 90 * 38 In this diagram, do the populations have equal or unequal variances? Unequal. 90 38 In this diagram, do the populations have equal or unequal variances? Unequal. 38 In this diagram, do the populations have equal or unequal variances? Unequal. 90 * * * * 35 Notice that the interval width is determined by 1-? in the sampling distribution. Have students explain why each of these occurs. Level of confidence can be seen in the sampling distribution. * * An estimator is a random variable used to estimate a population parameter (characteristic). Unbiasedness An estimator is unbiased if the mean of its sampling distribution is equal to the population parameter. Efficiency The efficiency of an unbiased estimator is measured by the variance of its sampling distribution. If two estimators, with the same sample size, are both unbiased, then the one with the smaller variance has greater relative efficiency. Consistency An estimator is a consistent estimator of a population parameter if the larger the sample size, the more likely it is that the estimate will come close to the parameter. * An estimator is a random variable used to estimate a population parameter (characteristic). Unbiasedness An estimator is unbiased if the mean of its sampling distribution is equal to the population parameter. Efficiency The efficiency of an unbiased estimator is measured by the variance of its sampling distribution. If two estimators, with the same sample size, are both unbiased, then the one with the smaller variance has greater relative efficiency. Consistency An estimator is a consistent estimator of a population parameter if the larger the sample size, the more likely it is that the estimate will come close to the parameter. * An estimator is a random variable used to estimate a population parameter (characteristic). Unbiasedness An estimator is unbiased if the mean of its sampling distr