随机抽样调查

This thesis has mainly contributed two results in theory: one is that the covariance matrix is not positive definitive if the number of sampling is least than the number of variables, the other is that the covariance matrix of discrete sample is positive definitive if and only if the sum of every random column vector of data matrix is non I-linear combination.

本论文在理论上，主要得出两个新的结果：ⅰ抽样调查中，若样本的个数少于变量的个数则样本协方差矩阵恒为非正定；ⅱ离散型样本协方差矩阵正定的充要条件是样本资料阵的各随机列向量是非I-线性组合。

Probability proportional sampling conducted according to various school sizes was used in this study to select subjects from all school nurses working at the elementary and junior high school levels.

研究采横断性调查法，研究工具为结构式问卷，采邮寄问卷方式以等比例分层随机抽样针对全国各学校单位之学校卫生护理人员进行抽样调查。

At present,the methods of random sampling,systematic sampling and stratified sampling are widely used in remote sensing sampling.

目前，随机抽样、系统抽样和分层抽样方式在遥感抽样调查技术领域应用比较广泛。

Methods: A cluster randomized sampling method was used to collect the samples from the storages in the houses of city inhabitants and the acaroid mites were identified and counted under the microscope.

采用整体随机抽样调查方法，采集淮南地区房舍储藏物标本，镜下进行粉螨分离鉴定，并结合哮喘的流行病学调查表统计数据，进行相关性分析。

Methods: Design: Crosssectional questionnaire survey. Measures: Demographic data, CDC (1994) CFS diagnostic criteria, Trudie Chalder fatigue scale, and China national standard for TCM syndrome types criteria.

按流行病学方法，参照英国Chalder等制订的疲劳量表、美国疾病控制中心1994年制定的CFS诊断标准及按《中药新药临床研究指导原则》中医证候指导原则的要求制定调查表，对香港地区20～50岁的普通公民进行非随机抽样调查。

Methods: Design: Crosssectional questionnaire survey. Measures: Demographic data, CDC (1994) CFS diagnostic criteria, Trudie Chalder fatigue scale, and China national standard for TCM syndrome types criteria. Subjects: Twenty to fifty years old adults by convenient sampling.

按流行病学方法，参照英国Chalder等制订的疲劳量表、美国疾病控制中心1994年制定的CFS诊断标准及按《中药新药临床研究指导原则》中医证候指导原则的要求制定调查表，对香港地区20～50岁的普通公民进行非随机抽样调查。

Methods Using "Rutter Child Behavior Scale" and Family Environment Factors Questionnaire to survey 4,863 school-age children aged between 6 and 13 years randomly.

运用&Rutter儿童行为量表&和家庭环境因素调查问卷，随机抽样调查4863名6~13岁在校学龄儿童行为问题及家庭环境因素。

Methods The constructions of food, the varieties and amounts of food absorption in 3 consecutive days were investigated. Each 50 families respectively from town, rural area, fishery region and district producing salt were chosen as random stratified sample during off-and peak seasons for seafood. The averaging daily IAC of each crowd was calculated based on the statistical forms of food composition and iodine concentration in food reported previously. The results were analyzed with SPSS software and then compared with Recommended Dietary Allowance recommended by ICCIDD.

分层随机抽样调查，于海产品供应丰、淡两季，在海岛城、农、渔、盐区各抽50户家庭，调查膳食结构及每人连续3 d摄入的食物和数量，以《食物成分表》及以往报道的食物中的含碘量为依据，计算人均每天IAC，并与国际控制碘缺乏病理事会制定的每日碘的推荐供给量比较。

Methods By using sampling investigation, three countries were selected in Yan'an, pupils' thyroids were examined by palpation and B-ultrasonograph; pupils and women were determined of their urinary iodine and the iodine salt in families; the students in the fifth grade and women of childbearing age and examined 6 ～ 14 year-old pupils'IQ.

用抽样调查的方法随机抽取了延安市3县，触诊和B超检查甲状腺情况，测定小学生及育龄期妇女尿碘，测定用户家中食用盐碘含量，对5年级学生及育龄期妇女进行问卷调查，测试6～14岁学生智商。

In order to have an estimate of rice yields obtained during 1991 by progressive farmers in a typical rice growing District of Gujranwala, a quick random survey was conducted by NFDC in collaboration with National Fertilizer Marketing Limited.

为了估计1991年古杰兰瓦拉典型稻区先进农民的水稻产量，国家肥料发展中心与国家肥料经销股份有限公司合作进行了一次快速随机抽样调查。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。