五章参数估计.pptVIP

38 In this diagram, do the populations have equal or unequal variances? Unequal. 90 90 大样本总体成数的置信区间 1. 假定条件 两类结果 总体服从二项分布 可以由正态分布来近似 使用正态分布统计量Ｚ 3. 总体成数Ｐ 的置信区间为 当p未知时，用 代替；无论用p或 ，其分布都将近似为正态分布 大样本总体成数的置信区间（实例） P219 三、大样本二总体均值、成数之差的区间估计（简单介绍一下，因为现实中用不到） 抽取简单随机样样本容量 n1 计算 X1 两个样本均值之差的抽样分布 m 1 s 1 总体1 s 2 m 2 总体2 抽取简单随机样样本容量 n2 计算 X2 计算每一对样本 的 X1- X2 所有可能样本 的 X1- X2 m1- m2 抽样分布 大家思考一个问题？为什么我们讲区间估计，讲了两种类型：一种是成数的区间估计；一种是均值的区间估计； 为什么呢？ 大样本区间估计的方法选择？考虑两个因素：数据类型：定类、定距？ 样本类型：单样本、双样本？ 大样本区间估计 小结P224 14 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. 43 33 Have students explain why each of these occurs. Level of confidence can be seen in the sampling distribution. 第五章 参数估计 第一节 统计推论 1. 什么是统计推论？ 统计推论就是根据样本的统计值去推断总