cluster sampling: When the Basic sampling unit in the population is to be found in groups or clusters the sampling is sometimes carried out by selecting a sample of clusters and observing all the members of each selected cluster.

• 整群抽样:一种抽样方法。当母体中的基本抽样单位是按群、组分类时,有时抽样方式是选择一类样本群组,然后对被选择的群组中的每一个样本单位的全体成员进行观察。