抽样单元

The present balanced two-layer sample rotation system is applicable only to the monthly survey with two-stage sample designs and with small primary sampling units.

目前的平衡两层次样本轮换模式只适用于一级单元规模较小时的两阶段抽样月度调查。

Unequal probability sampling is a very effective method for sampling applications,which is a sampling scheme with unequal probability .

不等概率抽样是赋予总体每个单元不完全相等入样概率的抽样，是实际中十分有效的抽样方法之一。

A 1∶250 00 standard map sheet (about 91 km 2) is used as a sampling unit in the western China's Xinjiang Uygur Autonomous Region and one county is used as a sampling unit in eastern China.

在黄淮海、长江中下游棉区采用县为单元的分层抽样的方法，抽样样本用遥感调查的方法获得。

First, this paper gives an introduction of some methods of unequal probability sampling, their estimators and variance estimators, including sampling with pps with replacement, methods of sampling without replacement suggested by Brewer, Durbin, Sampford , Des Raj , Murthy , Rao-Hartley-Cochran. Then, at the basis of Rao and Bayless's study , we consider that population can be splited two random subpopulations, which are respectively drawn from different infinite super-populations, and compare the stabilities of estimators of the methods that given above.

本文首先从理论上介绍了若干种不等概率抽样方法，它们的估计量、估计量的方差及其估计，其中包括有放回PPZ及PPS抽样，不放回不等概率抽样中的Brewer、Durbin、Sampford、Des Raj，Murthy、Rao-Hartley-Cochran等人的方法；其次，在Rao和Bayless两人就样本单元数n=2的情形对上述抽样方法进行比较的基础上，将总体随机地分成两个子总体，视每个子总体取自不同的线性超总体，在文中，我们利用计算机实现随机分组，并通过画图比较各方法估计量的稳定性，结果表明，对变异系数C.V。

First, this paper gives an introduction of some methods of unequal probability sampling, their estimators and variance estimators, including sampling with pps with replacement, methods of sampling without replacement suggested by Brewer, Durbin, Sampford , Des Raj , Murthy , Rao-Hartley-Cochran.Then, at the basis of Rao and Baylesss study , we consider that population can be splited two random subpopulations, which are respectively drawn from different infinite super-populations, and compare the stabilities of estimators of the methods that given above.

本文首先从理论上介绍了若干种不等概率抽样方法，它们的估计量、估计量的方差及其估计，其中包括有放回PPZ及PPS抽样，不放回不等概率抽样中的Brewer、Durbin、Sampford、Des Raj，Murthy、Rao-Hartley-Cochran等人的方法；其次，在Rao和Bayless两人就样本单元数n=2的情形对上述抽样方法进行比较的基础上，将总体随机地分成两个子总体，视每个子总体取自不同的线性超总体，在文中，我们利用计算机实现随机分组，并通过画图比较各方法估计量的稳定性，结果表明，对变异系数C.V。

A new data management algorithm for anycast based random sampling in sensor networks;2. Composite random sampling algorithm for scheduling concurrent projects;3. In the existing methods of random summing of total resource,the shape of the total resource curve sometimes distributes skewly,in view of which,the new method was put forward to improve random sampling .

针对现有的资源总量随机求和中存在的资源总量曲线形态有时呈偏态分布的问题，提出了对其随机抽样方法的改进方案，即把随机抽样入口由原来定义在(0，1)区间上改为定义在(0，ki)区间上(ki为第i个局部地质单元的石油资源量保险系数)，利用(0，ki)区间上均匀分布的随机数对风险分析后的资源总量分布函数进行随机抽样。

A type of probability sample in which aggregations of sampling units, called clusters, are sampled at some stage in the process.

是一种将样本单元聚集在一起的随机抽样法。样本群在抽样的某一步骤被抽出。

By the time of its fall, most of the prisoners were writers who had written against the corruptions of the government.

到它被攻陷的时候，里面多数的犯人是写了反对政府贪污文章的作家。

The most obvious variation to ovum morphological character was that the color was changed from light green to sepiaceous in embryonic development, and all the ovums were almost hatched after 96h.

在胚胎发育过程中卵的形态特征最明显的变化是颜色从淡绿到深褐色，卵在发育96h后卵基本全部孵化。