two-phase sampling

Two hundred subjects were selected by systematic sampling from non-English-major sophomores in Southwest Jiaotong University.

调查对象是西南交通大学二年级非英语专业的学生，经系统抽样，选取男女学生各100名完成问卷。

At last, a maximum likelihood estimating method of sampling frequency offset by transmitting two identical OFDM symbol was proposed.

通过连续重发两个相同的OFDM符号，应用最大似然估计方法确定采样频率偏差。

Methods Different high risk sites and the samples were selected by two-stage cluster sampling. All the samples were screened by HIV antibody test and RPR.

方法采用双阶段整群抽样方法抽取场所和样本，使用调查问卷面对面调查，采血检测HIV抗体和梅毒抗体。

To investigate the phenotypic plasticity and its ecological significance, lamina morphological and anatomic characteristics of Schisandra sphenanthera in different developmental stages, sampling from two populations located in Huangshan, Anhui, and Wenxian, Gansu, respectively, were examined.

分别对产自安徽黄山和甘肃文县的两个华中五味子种群不同发育阶段叶片的形态解剖特征进行比较，讨论了叶片表型可塑性及其生态学意义。

The Method of Mixed two-phase Stratified Sampling in Market Research; Methods Stratified chester random sampling.

市场调研中的混合双重分层抽样方法方法采用分层整群随机抽样的调查方法。

METHODS: From February to June 2004,15 students with normal eyesight ( including corrected vision) in the South Central University for Nationalities were tested in a whole reporting test and two sampling matching test.

方法：对15例2004-02/06中南民族大学学生视力（含矫正视力）正常者进行一项全部报告实验和两项抽样匹配实验。