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1.
基于六所部属师范大学数学专业免费师范生现状的调查数据,探讨是否允许考研和学习动力之间的关系.经典累积logistic模型对数据的拟合不佳.利用累积logistic混合模型,很好的拟合了数据,得到如果允许考研将提升免费师范生学习积极性的结论.  相似文献   

2.
为突出教师本人在评价中的主体地位,改变传统的至上而下的评价方式,针对高中数学教师评价指标体系设计问卷进行调查,运用项目反应理论(IRT)中的拓广分部评分模型(GPCM),应用Parscale统计软件对问卷调查结果进行统计分析,获得对高中数学教师评价指标体系的认同度.  相似文献   

3.
为探讨高级知识分子患脂肪肝的概率与肥胖、高血压、高胆固醇、高甘油三脂之间的关系 ,运用多因素数理统计分析方法对 4 91名副教授级以上教职工体检数据进行了分析。结果显示probit模型比 logistic模型能更好地拟合所分析的数据 ,而且脂肪肝与是否肥胖 ,是否高血压存在统计关联 ,既肥胖又患高血压的人患脂肪肝的概率是二者都正常的人的 2 .68倍。 χ2检验显示 ,患脂肪肝的男性显著高于女性。中国科大高级知识分子脂肪肝高检出率及其与肥胖、高血压关系的现象应引起足够重视  相似文献   

4.
偏最小二乘logistic回归在鄱阳湖洪涝灾害预测中的应用   总被引:3,自引:0,他引:3  
偏最小二乘logistic回归模型是一种新型的多元分析方法,它在自变量之间存在强多重共线性、或者当样本量偏小以及样本中有缺失值的情况下,可以较好地解决普通logistic回归模型的计算结果不稳定的问题.本文利用偏最小二乘logistic回归算法,根据鄱阳湖地区1953~1998年观测的水文数据,分析各月连续最大五天降水量和长江各月最大流量对鄱阳湖洪涝灾害的影响,建立了预测洪涝灾害程度的发生概率的判别模型.研究结果表明,偏最小二乘logistic回归模型在相关领域的研究中具有很好的适用性.  相似文献   

5.
采用调查问卷的形式,对北京市泰和小区、贵园南、北小区的居民和亦庄中心小学的家长进行垃圾分类知识的掌握情况,垃圾分类的态度意识,以及其对垃圾分类的处理方式等相关方面的了解.本文通过Pearson卡方检验来分析三个小区垃圾分类问题上的差异性;通过logistic回归,建立垃圾分类问题中居民的垃圾分类行为、居民的垃圾分类态度与垃圾分类知识的掌握情况之间的关系;同时,通过调查问卷来分析民众是否正确进行垃圾分类,并且分析民众将垃圾错误分类的原因何在,并提出合理有效措施以确保民众能够更好地进行垃圾分类.  相似文献   

6.
在许多情况下,我们需要对logistic回归模型中的重要变量进行选择,在本文中,我们对从信息论准则AIC选择出的模型给出了渐近分布和渐近概率。  相似文献   

7.
本文提出在超变异logistic回归模型中采用灵活的联系函数,文中研究了用统计程序包Genstat编写模型拟合程序的问题。我们把这一模型应用于人工授精试验数据的分析中,并对所得的结果与应用非超变异模型的结果进行了比较。  相似文献   

8.
基于对天山北坡经济带450个家庭的调查数据,通过构建双变量logistic模型,对该地区农户正规金融与非正规金融借款行为的影响因素进行估算.研究得到以下基本结论:1)影响农户借款行为的关键性和主要因素是农户家庭的特征;2)金融环境对农户借款行为影响显著;3)受民族聚居的影响,民族这一因素对地区农户借款的可获得性有所差异,对非正规金融借款行为的影响度高于对正规金融借款行为的影响.  相似文献   

9.
《数理统计与管理》2015,(6):1048-1056
中国人保守的消费习惯使得信用评级建模数据违约率较低,数据呈现出不平衡的特点,这种不平衡性对logistic回归模型的预测效果带来负面影响。本文将非对称连接函数的思想引入到信用评级中,将有偏logistic分布的分布函数作为连接函数的反函数,利用实际数据来估计偏度参数和回归系数。研究表明,有偏logistic回归的预测效果优于普通logistic回归,并且在10%的违约数据集中,有偏logistic回归的表现还优于决策树、神经网络和支持向量机。  相似文献   

10.
分析和研究消费者对再制造产品的认知程度及购买行为将有助于生产者进行决策.本研究通过在校大学生关于再制造产品的实际调查数据,运用描述性统计分析和Logistic计量模型分析,深入研究了大学生消费者对再制造产品的认知程度及其购买行为,并分别从消费者和产品两个角度对影响消费者购买行为的因素进行了研究,得出相关结论并提出了相关建议.  相似文献   

11.
中国优质企业环境会计信息披露决策研究   总被引:2,自引:0,他引:2  
环境保护是我国社会与经济能否实现可持续发展的关键,而环境保护必须通过企业行为得到落实,因此分析企业环境保护的积极性是经济理论和实践的迫切命题.选取代表我国优质企业的上市公司,利用Probit模型对它们环境信息披露的现状和披露的积极性进行分析研究,得出了能够对上市公司的环境会计信息披露倾向构成显著性影响的三个主要因素,它们为是否获得ISO14000环境管理体系认证、主营业务利润增长率的高低和国有股在该公司资本结构中所占比例.所研究的是国内首个通过计量方法分析企业环境会计信息披露倾向的影响因素的论文,具有较大的理论指导意义.  相似文献   

12.
杭州市水环境安全评价与预警模型   总被引:1,自引:0,他引:1  
水环境安全预警是城市水资源安全利用过程中不可或缺的一个重要环节.根据"压力-状态-响应"(PSR)模型,在充分考虑杭州市水环境实际状况的基础上,构建杭州市水环境安全评价指标体系;运用物元模型和可拓评价方法建立杭州市水环境安全预警模型.对杭州市历年的水环境实际样本数据进行分析与整理,利用预警模型对杭州市水环境安全现状进行评价,指出了影响杭州市水环境安全的恶化因素,对未来状况作出预警分析,并提出杭州市水环境安全的保障建议.  相似文献   

13.
The purpose of this paper is to provide a careful and accessible exposition of diffusive logistic equations with indefinite weights which model population dynamics in environments with strong spatial heterogeneity. We prove that the most favorable situations will occur if there is a relatively large favorable region (with good resources and without crowding effects) located some distance away from the boundary of the environment. Moreover we prove that a population will grow exponentially until limited by lack of available resources if the diffusion rate is below some critical value; this idea is generally credited to Thomas Malthus. On the other hand, if the diffusion rate is above this critical value, then the model obeys the logistic equation introduced by P. F. Verhulst.  相似文献   

14.
In this paper, we consider an SIS epidemic reaction–diffusion model with spontaneous infection and logistic source in a heterogeneous environment. The uniform bounds of solutions are established, and the global asymptotic stability of the constant endemic equilibrium is discussed in the case of homogeneous environment. This paper aims to analyze the asymptotic profile of endemic equilibria (when it exists) as the diffusion rate of the susceptible or infected population is small or large. Our results on this new model reveal that varying total population and spontaneous infection can enhance persistence of infectious disease, which may provide some implications on disease control and prediction.  相似文献   

15.
An SIS model with immigration for the spread of an infectious disease with bacteria and carriers in the environment is proposed and analyzed. It is assumed that susceptibles get infected directly by infectives as well as by their contacts with bacteria discharged by infectives in the environment. The growth rate of density of bacteria is assumed to be proportional to the density of infectives and decreases naturally as well as by bacterial interactions with susceptibles and carriers. The carrier population density is considered to follow the logistic model and grows due to conducive human population density related factors. It is assumed further that the number of bacteria transported by carriers to susceptibles is proportional to densities of both bacteria and carriers. The model study shows that the spread of the infectious disease increases due to growth of bacteria and carriers in the environment and disease becomes more endemic due to immigration.  相似文献   

16.
基于建设节约型社会和保护资源环境的需要,提出了一类特殊的双层规划问题,即B规划.给出了B规划的数学模型、有关理论和求解方法.最后还给出了B规划在矩阵对策中的一个应用.我们把局中人设有得失控制值的对策问题称为稳妥型对策.稳妥型矩阵对策可化为B规划问题求解.  相似文献   

17.
We propose a stochastic stage-structured single-species model with migrations and hunting within a polluted environment, where the species is separated into two groups: the immature and the mature, which migrates from one patch to another with different migration rates. By constructing a Lyapunov function, together with stochastic analysis approach, the stochastic single-species model admits a unique global positive solution. We then utilize the comparison theorem of stochastic differential equations to investigate the extinction and persistence of solution to stochastic single-species model. The main results indicate that the species densities all depend on the intensities of random perturbations within both patches. As a consequence, we further provide several strategies for protecting endangered species within protected and unprotected patches.  相似文献   

18.
We study the diffusive logistic equation with a free boundary in higher space dimensions and heterogeneous environment. Such a model may be used to describe the spreading of a new or invasive species, with the free boundary representing the expanding front. For simplicity, we assume that the environment and the solution are radially symmetric. In the special case of one space dimension and homogeneous environment, this free boundary problem was investigated in Du and Lin (2010) [10]. We prove that the spreading-vanishing dichotomy established in Du and Lin (2010) [10] still holds in the more general and ecologically realistic setting considered here. Moreover, when spreading occurs, we obtain best possible upper and lower bounds for the spreading speed of the expanding front. When the environment is asymptotically homogeneous at infinity, these two bounds coincide. Our results indicate that the asymptotic spreading speed determined by this model does not depend on the spatial dimension.  相似文献   

19.
In this article, we consider the effects of diffusion and time delay on the species in a polluted environment. Persistence-extinction thresholds are given for population in the toxicant stressed logistic growth model with discrete diffusion or time delay. It is proved that dispersal allows a larger threshold, that is, dispersal can increase the endurance effectiveness of the population subjected to toxicant, and time delay has no effect on the threshold result.  相似文献   

20.
Thresholds for extinction and persistence are important for assessing the risk of mortality in systems exposed to toxicant. In this paper, three single-species models with random perturbation in a polluted environment are proposed and investigated. One is the generalized logistic model and the other two are the stochastic resource–consumer models of Leslie and Gallopin. For each model, the survival threshold is obtained in some cases. In general, each threshold is determined by intensity of the random noise, the mean stress measure in organisms, the population intrinsic growth rate and the stress response rate.  相似文献   

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