Methods: The residents lived in two residential neighborhoods from an industrial and a cultural district were selected as objects of epidemic investigation by random sampling.
方法随机抽样以沈阳市区两个街道的常住居民为调查对象，进行有关哮喘的问卷调查，对疑诊患者行肺功能检查。
METHODS: a total of 283 families were investigated by random sampling, and the results of investigation were analyzed statistically.
方法采用非概率随机抽样方法，选取283户家庭进行调查，并对调查结果进行统计、分析。
Methods an investigation was made 1 000 old people aged 60 and upwards by random sampling and calling at the house.
方法采用整群随机抽样并进行入户调查的方法，对1 000名60岁及以上老年人进行了调查。
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