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The coefficient optimization for the multistage sampling rate conversion is also presented.
还给出了多级实现的系数优化算法。
Methods A total of 550 students in 4 junior schools were sampled with multistage sampling and surveyed.
方法通过多级随机抽样抽取济南市4所初中550名初一学生，采用问卷调查。
Methods Multistage sampling and stratified sampling were used and information was gathered by interview with questionnaires.
方法采用分层多阶段随机抽样法，获取样本。并采取问卷的形式进行调查。
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