随机抽样

Based on the precision and the cost of the relationship between the use of conditional extremum for the function of several variables method to determine when the first sample for sampling with probability proportion to size,the second-simple random sampling,the two-stage sampling is optimal allocation.

本文根据精度与费用之间的关系，利用求多元函数条件极值的方法，确定当第一级抽样为有放回PPS抽样，第二级抽样为简单随机抽样时，二阶抽样的样本容量最优分配。

Among probability sampling methods, what kinds of research conditions are more appropriate for each sampling method

什麼样的情况下，适合用机率抽样方法简单随机抽样有4种方法：1。简单随机抽样2。分层随机抽样3。系统抽样等距抽样

Excepting the conventional methods of surveying samples, such as simple random sampling, stratified sampling, cluster sampling, systematic sampling, liner regression sampling, ratio estimator, two-stage sampling, double sampling, rotate sampling, non-probability sampling, there is sequential sampling and mark-recapture, particularly mark-recapture was introduced in detail.

针对生物资源的调查，除了一般抽样方法如：简单随机抽样、分层抽样、整群抽样、系统抽样、双重抽样、二阶抽样、样本轮换、比率估计、线性回归抽样和不等概抽样，还有序贯抽样和标记-重捕获方法，这里特别详细介绍了标记-重捕获方法。

In chapter 10, we propose the random weighting approximation method for distribution of sample mean under simple random sampling in one-dimensional finite population.

第十章 将随机加权法首次应用到简单随机抽样方案下的样本均值分布逼近问题中，从数字特征角度说明了随机加权方法在抽样理论中的可用性，从而拓广了随机加权法的应用范围。

Simple random sampling; stratification ; ratio and regression estimates; systematic sampling, subsampling; cost functions and choice of optimal design; estimation procedures.

简单随机抽样，分层抽样、比率和回归估计，系统抽样、次级抽样，成本函数与最优设计选择；估计过程。

Most commonly, it begins with random cluster sampling and then applies simple random sampling or stratified random sampling

最常见的是，从随机整群抽样开始，然后应用简单随机抽样或者分层随机抽样

In principle, layered random sampling and simple random sampling were used.

取样原则采分层随机抽样和简单随机抽样方式，共抽取12所学校，抽样得70个班级，含68位教师与其班级学生共754人，回收的有效样本共计70班，合计68位级任教师与739位学生。

Firstly,the sampling design has great impact on the accuracy of remote sensing classification.There exists great randomicity on the result of points and cluster sample verification on the different Sampling design.On the same sampling design,the stability of point sample verification is higher than that of Cluster sample verification.Secondly,the average accuracy of different sampling designs of multi-point and multi-cluster sample verification can reflect the accuracy characteristic.During the course of point sample verification,stratified sampling's error is lower than others'.During the course of cluster sample verification,systematic sampling and stratified sampling's accuracy are prior to simple random sampling's.

研究结果表明：（1）抽样方式对遥感分类精度评价结果的影响是客观存在的，不同抽样方式下的点样本和群样本检验结果都存在一定的随机性，但同一种抽样方式下，点样本检验精度评估结果的波动幅度小于群样本检验，稳定性比群样本检验要好；（2）不同抽样方式下的多次点样本和群样本检验的平均精度检验结果基本上都能够反映分类图像的精度特征，其中，点样本检验中，分层随机抽样点样本检验效果较好；群样本检验中，系统抽样群样本检验和分层随机抽样群样本检验的效果优于简单随机抽样群样本检验。

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。

Even when the results under the two sampling systems were similar,typical mode sam- pling saved substantially cost and labor(by 2/5)and time(by 17/20)over random sampling.

即使两种抽样方法结果相近似，但典型众数抽样在布点、经费、人力及时间等方面比随机抽样为少，仅及随机抽样的3/5与3/20。

What are your goals and strategies for growth?

你的成长目标和策略是什么？

And unto the angel of the church in Sardis write; These things saith he that hath the seven irits of God, and the seven star I know thy works, that thou hast a name that thou livest, and art dead.

3：1 你要写信给撒狄教会的使者，说，那有神的七灵和七星的，说，我知道你的行为，按名你是活的，其实是死的。