讲解：STA 304H1F、Python，c++、Java，C++Python| Statistics、

STA 304H1F-1003H Fall 2019Assignment 2-Question 4Question 1. (5 marks)Consider a stratified design composed of H strata of size Nh, h = 1, . . . , H. We want toestimate the population mean µy of the characteristic y. Let µx,h, h = 1, . . . , H be the meansin the strata (in the population) of an auxiliary characteristic x. The µx,h are supposedlyknown and we propose to estimate µy using the following estimator:µbD = yst + µx − xstwhere yst and xst are the basic estimate of the population STA 304H1F代写、代做Python，c++程序设计、means µy and µx for y and x,respectively.(a) (1 mark) Give an expression of µx in terms of µx,h, h = 1, . . . , H.(b) (1 mark) Show that µbD is unbiased estimates for µy.(c) (1 mark) Give the variance of µbD(d) (1 mark) Let n =PHh=1 nh be the sample size. What is the optimal allocation of the nhin order to minimise the variance of µbD? We consider that the init cost of the surveydoes not depend on the stratum.(e) (1 mark) In which favourable case is µbD preferable to yst?1转自：http://www.3daixie.com/contents/11/3444.html