分层抽样

The sampling design of graduates＇ tracing survey in Hunan Radio and TV University follows the principles of randomicity, homogeneity and sampling trade representativeness and employs the method of delamination and isometry.

湖南电大开放教育试点专业毕业生追踪调查的抽样遵循随机性、分布相对均匀性、行业代表性等基本原则，采取分层等距抽样的方法。

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

Methods The stratified random sampling rule and the standard grading system of blindness set by WHO were adopted in the study, and 11 327 subjects were enrolled (a sampling fraction of 2.01%) in the whole county.

采用分层随机抽样原则，以世界卫生组织盲目分级为标准，对全县按2.01%抽样比例抽取11327例进行盲和低视力的流行病学调查。

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。

In this paper w e derived the optimum form of important function by variation method, with that proposed percepts to improve impor tant function; by utilizing the result of delaminateˉ sample theory, the improving direction of reˉsampling was determine d, and with that the double weight selecting partiˉ cle filtering was proposed.

为解决粒子滤波算法在实际应用中出现的滤波发散、粒子退化问题，文中利用变分法证明了重要性函数取法的最优形式，并由此提出重要性函数的改进方案；利用分层抽样原理，确定了重采样方法的改进方向，并由此提出双权重重采样方法。

The typic characteristic of this method is the dynamic adjustment of the sampling interval with the change of the network traffic.

作者在研究传统抽样方法和分层随机双抽样方法的基础上，提出自适应随机双抽样方法，该方法最显著的特征是能够随网络流量的变化动态调整抽样间隔。

000 People （at the age of 18 -69 ） were investigated through sampling and analyzed by adopting the method of delaminating cluster sampling and the test system on scientific literacy conflated by the Scientific Association of China and the questionnaires.

按照中国科协制定的科学素养测试体系和问卷模式，采取分层抽样方法，对柳州市3000名18岁-69岁公众进行抽样调查。

Methods a cluster stratified sampling method was used to chose 3 989 pupils from six schools of different levels in xiamen. they were investigated with conners parent symptom questionnaire.

采用整群分层抽样法抽取厦门市6所不同层次的小学一～五年级学生3 989名为调查对象，应用conners量表进行调查，dsm-ⅳ诊断标准确诊。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失