共查询到20条相似文献，搜索用时 46 毫秒
1.
Data analysis requires subtle probability reasoning to answer questions like What is the chance of event A occurring, given that event B was observed? This generic question arises in discussions of many intriguing scientific questions such as What is the probability that an adolescent weighs between 120 and 140 pounds given that they are of average height? and What is the probability of (monetary) inflation exceeding 4% and housing price index below 110? To address such problems, learning some applied, theoretical or cross‐disciplinary probability concepts is necessary. Teaching such courses can be improved by utilizing modern information technology resources. Students' understanding of multivariate distributions, conditional probabilities, correlation and causation can be significantly strengthened by employing interactive web‐based science educational resources. Independent of the type of a probability course (e.g. majors, minors or service probability course, rigorous measure‐theoretic, applied or statistics course) student motivation, learning experiences and knowledge retention may be enhanced by blending modern technological tools within the classical conceptual pedagogical models. We have designed, implemented and disseminated a portable open‐source web‐application for teaching multivariate distributions, marginal, joint and conditional probabilities using the special case of bivariate Normal distribution. A real adolescent height and weight dataset is used to demonstrate the classroom utilization of the new web‐application to address problems of parameter estimation, univariate and multivariate inference. 相似文献
2.
对于双缝衍射实验,概率幅的迭加原理是指当两条缝同时打开时,一个电子通过某一条缝达到屏幕上某处的概率幅等于两条缝轮流打开时,该事件的两个概率幅之和.从这一原理得出结论：概率本身不遵循迭加原理,而这就是经典概率论不适用于微观过程的原因.柯氏概率论立足于概率的频率定义与事件运算的布尔代数两大基石,在微观过程中,概率的频率定义仍然有效,但事件运算不再遵循布尔代数的规则,特别是不遵循其乘法的交换律.因此,只要不涉及事件运算,柯氏概率论的联合概率的概念还是可以用于微观过程.但是当涉及事件运算时,将联合概率的运算公式应用于微观过程很可能得出错误的结论,贝尔不等式就是这样一个错误的结论. 相似文献
3.
This study investigated whether vicarious feedback influences binding processes between stimuli and observed responses. Two participants worked together in a shared color categorization task, taking the roles of actor and observer in turns. During a prime trial, participants saw a word while observing the other person executing a specific response. Automatic binding of words and observed responses into stimulus-response (S-R) episodes was assessed via word repetition effects in a subsequent probe trial in which either the same (compatible) or a different (incompatible) response had to be executed by the participants in response to the same or a different word. Results showed that vicarious prime feedback (i.e., the feedback that the other participant received for her or his response in the prime) modulated S-R retrieval effects: After positive vicarious prime feedback, typical S–R retrieval effects emerged (i.e., performance benefits for stimulus repetition probes with compatible responses, but performance costs for stimulus repetition probes with incompatible responses emerged). Notably, however, S–R-retrieval effects were reversed after vicarious negative prime feedback (meaning that stimulus repetition in the probe resulted in performance costs if prime and probe responses were compatible, and in performance benefits for incompatible responses). Findings are consistent with a flexible goal imitation account, according to which imitation is based on an interpretative and therefore feedback-sensitive reconstruction of action goals from observed movements. In concert with earlier findings, this data support the conclusion that transient S–R binding and retrieval processes are involved in social learning phenomena. 相似文献
4.
Michael C. Neale Shaunna L. Clark Conor V. Dolan Michael D. Hunter 《Structural equation modeling》2016,23(2):221-233
A linear latent growth curve mixture model with regime switching is extended in 2 ways. Previously, the matrix of first-order Markov switching probabilities was specified to be time-invariant, regardless of the pair of occasions being considered. The first extension, time-varying transitions, specifies different Markov transition matrices between each pair of occasions. The second extension is second-order time-invariant Markov transition probabilities, such that the probability of switching depends on the states at the 2 previous occasions. The models are implemented using the R package OpenMx, which facilitates data handling, parallel computation, and further model development. It also enables the extraction and display of relative likelihoods for every individual in the sample. The models are illustrated with previously published data on alcohol use observed on 4 occasions as part of the National Longitudinal Survey of Youth, and demonstrate improved fit to the data. 相似文献
5.
随机变量相依关系的度量 总被引：1，自引：1，他引：0
严忠权 《黔南民族师范学院学报》2008,28(6):34-38
首先研究了相关系数在度量随机变量相依关系上的优点和缺陷,介绍了度量随机变量相依关系的理想统计量应具备的条件,针对联合分布可拆成一元边际分布和Copula的积,因此连接联合分布与边际分布的Copula函数应包含随机变量相依关系的一切信息,在此基础上给出了基于Copula函数表示的Spearman’s相关系数和Kendall’s相关系数以及它们的性质． 相似文献
6.
Nineteen percent of 1997–98 North Carolina 3rd graders were observed to drop out of high school. A series of logits predict probabilities of dropping out on determinants such as math and reading test scores, absenteeism, suspension, and retention, at the following grade levels: 3rd, 5th, 8th, and 9th. The same cohort and variables are used to estimate benefits to the 15,737 students admitted to a special program ostensibly for academically and intellectually gifted children. I estimate the probability of admission for schoolmates with similar ability in math and reading to be substantially higher for those from upper income households. Finally, I conclude that extending similar resources to an equal number of high-risk students, as determined by their 3rd grade predicted probabilities, would lead to a 25% reduction in the total cohort dropout rate, and that even dividing existing resources between the two groups could cut dropout rates by half that. 相似文献
7.
提出了一种多主从用户相互协作的认知共存网络系统模型.在该模型中,控制中心已知所有用户的位置并为每个主用户分配最近的从用户进行协作通信,控制中心通过从用户反馈的感知结果来获取频谱空洞信息并为从用户分配工作频段.主用户利用正交子信道接入基站.从用户利用网络中未用的频谱空洞采用放大前传机制为主用户转发数据.推导了在该模型下主用户的中断概率,并对主用户发送概率ps、主从用户间发射功率分配系数ξ和主从用户数对系统的影响进行了仿真.仿真结果表明,主从用户间平均分配发射功率在ξ=0.5且网络中主从用户数目相同时系统性能最优. 相似文献
8.
Twenty acquisition curves were obtained from each of 8 pigeons in a free-operant choice procedure. Every condition began with a phase in which two response keys had equal probabilities of reinforcement, and, as a result, subjects’ responses were divided fairly evenly between the two keys. This was followed by a phase in which one key had a higher probability of reinforcement than the other, and the development of preference was observed. In all but a few cases, response proportions increased for the key with the higher probability of reinforcement. In most conditions, the two probabilities differed by .06, but the actual probabilities varied (from .16 and .10 in one condition to .07 and .01 in another). Development of preference for the key with the higher probability of reinforcement was slower when the ratio of the two reinforcement probabilities was small (.16/.10) than when it was large (.07/.01). This finding is inconsistent with the predictions of several different quantitative models of acquisition, including the kinetic model (Myerson & Miezin, 1980) and the ratio-invariance model (Horner & Staddon, 1987). However, the finding is consistent with a hypothesis based on Weber’s law, which states that the two alternatives are more discriminable when the ratio of their reinforcement probabilities is larger, and, as a result, the acquisition of preference is faster. 相似文献
9.
文章利用,Monte-Carlo方法来计算一种特殊的概率,这种概率不能或极难用定积分的方法计算得到,但与一般的Monte-Carlo方法不同的是由于问题的特殊性,要求给随机变量赋予一个服从正态分布且要介于某个区间的随机数。文章设计的算法不仅对这种概率有效,而且还可以推广,用以计算两个或两个以上的与此有关的概率。 相似文献
10.
在WEB环境下的（Geographical Information System-GIS）的应用程序中,客户端的用户浏览空间对象集合具有明显的访问局部性。本文提出了一种在空间查询中利用H illbert曲线空间局部性特性预先提取空间数据的空间优化方法,该方法充分利用用户访问模式的特点大大提高了在空间数据库上执行空间查询的响应时间,最后给出了优化方法的算法伪代码以及在MAPGIS平台上的试验分析数据。 相似文献
11.
This article proposes a new type of latent class analysis, joint latent class analysis (JLCA), which provides a set of principles for the systematic identification of the subsets of joint patterns for multiple discrete latent variables. Inferences about the parameters are obtained by a hybrid method of expectation-maximization and Newton–Raphson algorithms. We apply JLCA in an investigation of adolescent violent behavior and drug-using behaviors. The data are from 4,957 male high-school students who participated in the Youth Risk Behavior Surveillance System in 2015. The JLCA approach identifies the different joint patterns of 4 latent variables: violent behavior, alcohol consumption, tobacco cigarette smoking, and other drug use. The JLCA uncovers 4 common violent behaviors and 3 representative behavioral patterns for each of 3 other latent variables. In addition, the JLCA supports 3 common joint classes, representing the most probable simultaneous patterns for being violent and being a drug user among adolescent males. 相似文献
12.
John C Turner 《Teaching Statistics》1998,20(2):46-48
Using the spreadsheet function SUMPRODUCT which calculates dot products, it is possible to compute the probabilities associated with the sums of independent discrete random variables. This allows the student to confirm properties of the sum of binomial and Poisson random variables. It also provides a method for computing the distribution of the sum of two (or more) arbitrary random variables. In addition, it also allows the student to compute the probabilities associated with the difference of random variables, and thus find the probability that one random variable exceeds another (or exceeds by a given amount). 相似文献
13.
分析了基于物种敏感度分布（SSD）的概率生态风险评价的数学原理，并在此基础上首次给出了概率生态风险评价的Matlab函数"PERA"，该函数只需要污染物的生物毒性数据和环境监测数据作为输入变量即可获得SSD曲线、HC5值、联合概率曲线（JPC）以及JPC与坐标轴所围面积表示的发生有害生物效应的总体风险概率（ORP值）等指标，可用于污染物环境基准的推导和污染物生态风险评价。 相似文献
14.
Thomas H. Turney 《Learning & behavior》1976,4(4):363-366
Long-Evans rats were trained on an easy simultaneous discrimination problem and then transferred to a hard discrimination problem. The discriminanda were different orientations of stripes. In Experiment I, transfer was intradimensional with stimulus generalization controlled. The easy-to-hard effect was not found. In Experiment II transfer was intradimensional and either compatible (nonreversal) or incompatible (reversal). With compatible transfer, rats trained on a prior easy problem learned the hard problem faster than rats trained only on the hard problem. Persistent negative transfer was found with incompatible transfer. Attention was not supported as underlying the easy-to-hard effect. Explanations based on specific sources of intradimensional transfer, such as stimulus generalization or adaptation level, are suggested. 相似文献
15.
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
16.
房再胜 《临沂师范学院学报》2014,(6):34-37
设总体具有连续的分布函数F(x)以及概率密度f(x),X(1),X(2),...,X(n)为次序统计量.利用边缘(际)分布密度给出求部分次序统计量的联合密度的一般求法. 相似文献
17.
A defining characteristic of continuous queries over on-line data streams, possibly bounded by sliding windows, is the potentially infinite and time-evolving nature of their inputs and outputs. For different update patterns of continuous queries, suitable data structures bring great query processing efficiency. In this paper, we proposed a data structure suitable for weak non- monotonic update pattern in which the lifetime of each tuple is known at generation time, but the length of lifetime is not necessarily the same. The new data structure combined the ladder queue with the feature of weak non-monotonic update pattern. The experiment results show that the new data structure performs much better than the traditional calendar queue in many cases. 相似文献
18.
病害对植物生产的影响一直是科技工作者十分关注的问题,植物致病是指由真菌、细菌、病毒、类病毒等病原物通过机械擦伤、昆虫介导或直接插入寄主细胞后通过多种手段使植物产生的不良反应。病原和寄主的关系有亲和和不亲和两种,其中亲和则寄主表现感病,反之则抗病。而寄主的抗病机理又因为抗病基因和防卫基因的不同而不同。本文将从这些方面对植物抗病分子机理进行简要的阐述。 相似文献
19.
医院图书馆需要一个完善的图书管理系统来实现对图书、用户以及借阅进行统一管理。实现文献信息的高度共享,应用现代信息技术科学地共享信息资源．本文通过对医院图书馆管理系统的需求分析和用例分析。基于B／S和C／S体系架构,建立了医院图书管理信息系统．系统包括：信息管理、图书信息管理、用户信息管理、图书借阅管理、报表统计管理等五个模块,本文介绍了系统部分模块的设计和实现方法． 相似文献
20.
概率的定义有两种稍微不同的陈述方式,按照第一种陈述,相对频率就是概率;按照第二种陈述,相对频率与概率是不同的概念概率依赖于观察者;相对频率则与观察者无关.只有在一定条件下,这两个不同含义的量才在数值上相等.关于概率的许多争论,特别是概率的主观诠释与客观诠释之间的争论,都与这两种陈述的微妙区别有关.波普尔采用的是第一种陈述,但他也承认存在第二种陈述.在此基础上他创建了一个复杂的概念体系.本文将考察波普尔的这一概念体系. 相似文献