two-stage sampling

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。

Now internationally recognized, JPEG 2000 technology applies two-dimensional filtering and sub-sampling in hierarchical and multi-step combinations.

现在,国际公认的JPEG2000技术应用于分层的和多步融合的二维滤波和二段抽样.

When the sampling consume index ( C 1/ C 2) of the primary unit and secondary unit for two-stage sampling equals 10, the optimum sampling number of secondary unit is 5 or 6 twigs at each density.

当二阶抽样的初级单元与次级单元的消耗指标C1／C2＝10时，在各种密度下次级单元的最适抽样量为每样株5～6个枝条；

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 first concern in this chapter is to compute aggregation parameter which reflects the aggregation level of the spatial point pattern. Two new methods, K-function and distance sampling, are proposed.

本章首先给出了两种计算点格局聚集指数的方法，K-function以及邻体距离抽样方法。

This study adopted two-stage random sampling method. The valid subjects were 300.

本研究采二阶段随机抽样方法, 有效样本共300位.

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。