9.1 Basic Concepts in Samples and Sampling
9.1.1 Population and census
Population(总体): the entire group under study as defined by research objectives
A census(普查) is an accounting of the complete population.
9.1.2 Sample and Sample Unit
Sample(样本): a subset of the population that should represent the entire group
能够代表整个总体情况的总体子集
Sample unit(样本单位): the basic level of investigation
调研中最基本的被调查者
9.1.3 Sample Frame and Sample Frame Error
A sample frame(抽样框): a master list of the entire population
总体中总体单位的总清单,可能存在与总体不一致的问题
总体中样本单位的主要来源
Sampling frame error(抽样框误差): the degree to which the sample frame fails to account for all of the population
抽样框不能反映整个总体的程度
9.1.4 Sampling error
Sampling error(抽样误差): any error in a survey that occurs because a sample is used
因调查中使用样本而产生的误差
样本选择方法(抽样框)与样本容量都会影响抽样误差
9.1.5 Reasons for Taking a Sample
1. Practical considerations such as cost and population size
2. Inability of researcher to analyze huge amounts of data generated by census
3. Samples can produce precise results

