【简答题】Child mortality (死亡率) decreased due to improvements in medical care and greater attention to problems related to proper ________.(gigantic; standpoint; evacuate; naïve; permeate; nutrition; inflict; s...
【简答题】Liam works in Sydney. Last week he had 41 holiday, but he didn’t know 42 to go. He said to his friend Robert, “I 43 the hot weather here, but I can’t find a cool place in Australia. How will I spend m...
【简答题】先将总体划分成若干群,然后以群作为抽样单位从中随机抽取部分群,再对抽中的各个群中所包含的所有元素进行观察。该抽样方法为( )。
【单选题】Child mortality (死亡率)decreased due to improvements in medical care and greater attention to problems related to proper________.
【简答题】简述随机抽样与非随机抽样的含义及各自具体包含哪些抽样方法。
【单选题】How does Will feel in his last times from the passage? (from P.470-476)
A.
He looks anxious and guilty
B.
He is pretty composed and relaxed
C.
He feels pressured and reluctant
【简答题】Whether he will invest his last sum in that project is a case of _____ or swim for him.
【简答题】设随机变量X和Y的相关系数为0.9,若Z=X-0.4,则Y与Z的相关系数为________.
【单选题】将总体中的全部个体区分为容量及结构相似的不同的子总体,以子总体为单位按照简单随机抽样的方法抽取一定数量的子总体,再将这些被抽中的子总体中所包含的个体合并起来形成最终的样本,这种抽样方法称作