At the national level it is easy enough, though expensive, to account for this by surveying CPOs and including them in the sample in proportion to their share of the population.
尽管昂贵，但从国家水平来看，民意调查如按CPOs在总人口中所占的比例计算，调查就会很容易。
At the national level it is easy enough, though expensive, to account for this by surveying CPOs and including them in the sample in proportion to their share of the population.
尽管昂贵，但从国家水平来看，民意调查如按CPOs在总人口中所占的比例计算，调查就会很容易。
应用推荐