“全国0～14岁儿童智力低下流行学调查”是国家七五攻关科研项目之一,其目的是了解我国城乡智力低下的患病率和病因学,给国家制定对本病的防治措施提供科学依据。我省是参加本项调查工作的六省二市之一。本调查采取分层不等比例多阶段随机整群抽样方法抽取样本,各省城市包括省会和一个省辖市,农村各县按经济等因子分析分为上、中、下三类进 “National 0 to 14-year-old children mental retardation epidemiological survey” is one of the national 75 research projects, its purpose is to understand the prevalence and etiology of mental retardation in urban and rural areas in China, to provide the state with the prevention and treatment measures to provide the disease in accordance with. Our province is one of the six provinces and two cities that participated in the survey. In this survey, stratified unequal proportions of multistage random cluster sampling methods were used to extract samples. Provinces include provincial capitals and a provincial municipality. The rural counties are divided into upper, middle and lower categories according to economic factors and other factors