共查询到20条相似文献，搜索用时 234 毫秒
1.
通过对“有放回”与“无放回”、“排列”与“组合”、“相同”与“不同”三类概念区别的分析,避免了在概率计算中概念的混淆 相似文献
2.
二阶抽样下样本容量最优分配 总被引：2，自引：0，他引：2
样本容量的确定是抽样调查中的一个重要内容。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。 相似文献
3.
《中学生数理化(高中版)》2016,(1)
<正>考点一简单随机抽样例1下列抽取样本的方式是否属于简单随机抽样?(1)从无限多个个体中抽取100个个体作为样本。(2)盒子里共有80个零件,从中选出5个零件进行质量检验。在抽样操作时,从中任意拿出一个零件进行质量检验后再把它放回盒子里。(3)从20件玩具中一次性抽取3件进行质量检验。(4)某班有56名同学,指定个子最高的5名同学参加学校组织的篮球赛。解析:(1)不是简单随机抽样。因为被抽 相似文献
4.
(续上期 )6 简单随机抽样有哪些特点 ?答 :( 1 )它要求被抽取的样本总体的个数有限 ,以便对其中各个体被抽取的概率进行分析。( 2 )这种抽样是从总体中逐个进行抽取 ,这就使得它具有可操作性。( 3 )这是一种不放回抽样。由于在抽样的实践中常常采用不放回抽样 ,使简单随机抽样具有较广泛的实用性 ,而且由于在所抽取的样本中没有被重复抽取的个体 ,所以便于进行分析与计算。( 4 )这是一种等概率的抽样。不仅每次从总体中抽取一个个体时 ,各个体被抽取的概率相等 ,而且在整个抽样过程中 ,各个体被抽取的概率也相等 ,从而保证了这种抽样方法的… 相似文献
5.
王伟 《宁波职业技术学院学报》2007,11(5):10-11,23
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。πps抽样是与单元大小成比例的不放回不等概率抽样。通过实际例子对πps抽样方法与简单随机抽样方法进行了对比,表明πps抽样方法能够提高样本对总体的代表性和可行性。 相似文献
6.
随机抽样又可分成多种具体的方法,教育调查中常用的随机抽样有简单随机抽样、等距随机抽样和分层随机抽样三种,在抽样时我们可以根据研究对象总体的具体情况、研究者可以动用的力量和课题研究对抽样质量的要求从中加以选择。 一、简单随机抽样 简单随机抽样是随机抽样中最简单的一种方法,又被称为单纯随机抽样。简单随机抽样对研究总体的对象不进行重新组合,只是按照随机原则直接从总体中抽取样本。简单随机抽样可以采取抓阄法、随机数字表法和随机函数法等方式进行。 1抓阄法。抓阄法又称抽签法。具体的抽取过程是：先将… 相似文献
7.
制造业是甘肃省国民经济增长的主要源泉,其产业绩效的评价与分析对甘肃省产业政策的制定具有重要的指导意义。本文选取了甘肃省及全国的相关统计数据,运用DEA模型,对甘肃省制造业的效率进行了实证研究,结果表明,甘肃省制造业绩效在整体水平不高,并且制造业中高技术行业在纯技术方面相对无效率,而低技术行业则在规模技术方面相对无效率。 相似文献
8.
通过建立实证研究分析框架,对1996—2006年间发表在我国9种外语类核心期刊上的59篇实证研究文献进行了质量调查。结果发现：五分之一的研究报告理论依据不充分;半数以上设计方案上有不同程度的缺陷;三分之二以上测量工具缺乏信度或效度;五分之一以上数据分析方法有误;近五分之一的研究对结果的解释有漏洞;近五分之四的研究总体质量有不同程度的缺陷。 相似文献
9.
概率计算题型中,解题时经常要我们分清"有序"与"无序"、"有限"与"无限"、"有放回"与"无放回"等条件的影响,笔者将这些问题形象的概括为"三有"与"三无"问题,对这些问题进行简单剖析,供广大读者参考.一、"有序"与"无序"问题在古典概率计算题型中,经常要区分"有序"还是"无 相似文献
10.
在抽样调查中,通常的简单随机抽样是指每次从总体中抽取一个单位,抽后都放回到总体中,或者抽后都不放回。但是在实际问题中,由于经济上的原因,或者为了抽样的快速,或者为了提高抽样精度,就产生了抽样进程中某些单位放回到总体中,而另外一些单位不放回到总体中的抽样方法,我们称之为返回与不返回混合简单随机抽样。 设总体Ω_N={Y_1,…,Y_N},从Ω_N中抽取容量为n的简单随机样本y_1,…y_n,其中y_1,……y_（n_1）是前n_1次抽取的结果,y_(n_1+1),……y_(n_1+n_2)是后n_2 次抽取的结果（n=n_1+n_2),并且令 相似文献
11.
胡洪彬 《江苏广播电视大学学报》2008,19(6):70-73
政府执行力的强弱,关系到政府职能的实现、政府存在的合法性和行政效率的高低。近年来国内理论界对政府执行力的研究,取得了许多理论成果,但也存在一些问题和不足。今后应加强比较研究和实证调研,并进一步强化对其多视角和多学科的探讨． 相似文献
12.
Marie-Christine Opdenakker Jan Van Damme 《School Effectiveness & School Improvement》2013,24(1):103-130
In this article, the effect of ignoring one or more levels of variation in hierarchical linear regression analysis is explored. A model with four hierarchical levels is used as a reference model. A distinction is made between ignoring top and intermediate levels. The effects of ignoring levels on the fixed and on the random parameters of different random intercept models are explored by means of a real data set. The results show that ignoring an important level causes an effect on specific fixed coefficients, variance components and their corresponding standard error. Therefore, ignoring an important level can lead to different research conclusions. 相似文献
13.
One common phenomenon in Angoff standard setting is that panelists regress their ratings in toward the middle of the probability scale. This study describes two indices based on taking ratios of standard deviations that can be utilized with a scatterplot of item ratings versus expected probabilities of success to identify whether ratings are regressed in toward the middle of the probability scale. Results from a simulation study show that the standard deviation ratio indices can successfully detect ratings for hard and easy items that are regressed in toward the middle of the probability scale in Angoff standard‐setting data, where previously proposed indices often do not work as well to detect these effects. Results from a real data set show that, while virtually all raters improve from Round 1 to Round 2 as measured by previously developed indices, the standard deviation ratios in conjunction with a scatterplot of item ratings versus expected probabilities of success can identify individuals who may still be regressing their ratings in toward the middle of the probability scale even after receiving feedback. The authors suggest using the scatterplot along with the standard deviation ratio indices and other statistics for measuring the quality of Angoff standard‐setting data. 相似文献
14.
Ruben Georges Fukkink Noortje Trienekens Lisa J. C. Kramer 《Educational Psychology Review》2011,23(1):45-63
This meta-analysis demonstrates that the video feedback method has a statistically significant effect on the interaction skills
of professionals in a range of contact professions. The aggregate effect, calculated on the basis of 217 experimental comparisons
from 33 experimental studies involving a total of 1,058 people, was 0.40 standard deviation (SE = 0.07). The effects of training
were greater for programs working with a standard observation form of target skills that were central to the program. Results
were more positive for outcome measures that measured positive skills rather than negative ones. In addition, molar outcome
measures, which were obtained by means of an assessment scale, showed larger effects than micromeasures, which were scored
using event sampling. Finally, recommendations are made for video feedback design and for future research. 相似文献
15.
The effect of research article length, format, and technical quality upon practicing counselors' receptivity to research material was examined. A group of 160 school and rehabilitation counselors were selected by a stratified sampling procedure and assigned at random to one of eight treatment conditions. Each of these treatments represented a combination of predictor variables. Subject ratings of the research articles were analyzed using a least squares analysis of variance procedure. Contrary to much of the available literature, it was found that none of the predictor variables significantly affected scores of counselor receptivity in any consistent direction or between articles of different content. 相似文献
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17.
《Journal of research on educational effectiveness》2013,6(1):114-135
Abstract Randomized experiments are often seen as the “gold standard” for causal research. Despite the fact that experiments use random assignment to treatment conditions, units are seldom selected into the experiment using probability sampling. Very little research on experimental design has focused on how to make generalizations to well-defined populations or on how units should be selected into an experiment to facilitate generalization. This article addresses the problem of sample selection in experiments by providing a method for selecting the sample so that the population and sample are similar in composition. The method begins by requiring that the inference population and eligibility criteria for the study are well defined before study recruitment begins. When the inference population and population of eligible units differs, the article provides a method for sample recruitment based on stratified selection on a propensity score. The article situates the problem within the example of how to select districts for two scale-up experiments currently in recruitment. 相似文献
18.
本文对宜春以打造“江南生态休闲城市”为目标的城市发展定位进行了实证分析,在此基础上提出了宜春打造“江南生态休闲城市”的总体思路和一些具体对策。 相似文献
19.
本文认为应以高校教师职业特性为切入点来研究高校人才环境.通过研究"研究型高校"教师职业特性及其对人才环境的内在规定,建立了"研究型高校"教师职业特性与人才环境特性之间的规定关系模型和研究型高校人才环境标准模型,并运用标准模型分析了我国研究型高校人才环境的实际状况和建立研究型高校人才环境监控系统的必要性,从而建立了研究型高校人才环境监控系统模型.本研究为建立和维护研究型高校人才环境的良好生态提供重要的理论基础. 相似文献
20.
江苏产业结构与就业结构关系的实证分析 总被引：2，自引：0，他引：2
廖新平 《湖南科技学院学报》2006,27(7):140-142
经济发展过程中,产业结构和就业结构都发生着变化。本文利用结构偏离度指数对江苏省产业结构和就业结构进行了实证研究,得出结论：江苏省第一产业的产业结构与就业结构具有相关性,第二产业的产业结构与就业结构呈微弱负相关,第三产业的产业结构与就业结构相关性较强,就业人口已开始向第三产业转移。 相似文献