共查询到15条相似文献,搜索用时 140 毫秒
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Gompertz模型和Logistic模型的拟合 总被引:15,自引:1,他引:14
朱珉仁 《数学的实践与认识》2002,32(5):705-709
常见的三参数 S形生长模型有 Gompertz模型和 L ogistic模型 .它们在拐点处的坐标、导数与它们的参数是能够相互唯一确定的 .当利用拟事隐函数曲线的 GNL 法对这两种模型进行最小二乘拟合时 ,可根据这一性质对单个未线性化参数的初始值进行搜索 .有时也可对该初始值直接进行搜索 .最后以几个实例成功地对这种算法进行了验证 相似文献
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用循环搜索法确定单个未线性化参数的初始值 总被引:2,自引:1,他引:1
朱珉仁 《数学的实践与认识》2004,34(1):80-87
在最小二乘意义下用 GNL法拟合常见的三参数隐函数曲线时 ,用循环搜索法确定了单个未线性化参数初始值 .并成功地以多个著名模型为例对此进行了验证 . 相似文献
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朱珉仁 《数学的实践与认识》2004,34(8):108-114
在最小二乘意义下用 GNL法拟合了常见的四参数隐函数曲线 .将用循环搜索法确定初始值的未线性化参数数量由一个推广到两个 .并成功地以多个著名模型为例对此进行了验证 . 相似文献
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在非线性回归模型参数拟合问题中,当数据中的每个变量都存在不可忽略的误差时,在普通的最小二乘准则下拟合出的参数不是最优的.按照总体最小二乘准则,以观测点到拟合曲线或拟合曲面垂直距离平方和为目标函数,然后用最优化方法搜索出使目标函数值取最小值的参数和数据点估计,从而给出求最优模型参数的算法,最后,通过计算机仿真和与文献比较,验证了提出方法的正确性. 相似文献
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谭诗斌 《数学的实践与认识》2023,(7):154-168
在传统Beta模型基础上,采取与e指数n次多项式函数乘积方式,构造了一种参数可有限扩展的线性模型——Beta柔性扩展模型.据对全国数学建模分组数据的拟合实验,该模型的均方误差达到10-9数量级水平.对19个国家收入分配分组数据进行多个模型的估计误差对比,证明该模型的拟合质量总体上优于对比模型.探索性提出的“固定参数+柔性参数”线性建模方式和“递次回归、择优筛选”的分组数据逼近机制,为提高洛伦兹曲线拟合精度提供了一种可参考的新方法、新选择. 相似文献
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陆付民 《数学的实践与认识》2007,37(19):6-11
考虑到对于处于不同位置的变形监测点,由于它们所处的位置不同,各种环境因素对它们的影响及影响程度也不同,作者预置数个AR(n)模型,通过计算比较,选择剩余标准差最小的AR(n)模型作为初选模型,再将初选的AR(n)模型的模型参数看作包含有动态噪声的状态向量,建立卡尔曼滤波模型.实例分析表明,采用这种方法能够提高模型的拟合精度和预测精度. 相似文献
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Richards模型参数估计及其模型应用 总被引:5,自引:0,他引:5
程毛林 《数学的实践与认识》2010,40(12)
在非线性模型中,Richards模型是一个含有四参数的增长曲线模型,该模型对数据的拟合有较强的适应性,应用较为广泛.但其参数的估计较为复杂,给出简便易行的三种方法,实例应用表明拟合效果很好. 相似文献
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程毛林 《数学的实践与认识》2009,39(9)
对非线性回归模型进行非线性最小二乘估计一般需要确定参数初始值.在非线性回归模型中,General Logistic模型和Von Bertalanffy模型是二个含有四参数的增长曲线模型,对数据的拟合有较强的适应性,应用较为广泛.本文给出这两个模型参数初始值的确定方法,并应用于实际拟合,得到很好的效果. 相似文献
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Waleed A. Muhanna 《Annals of Operations Research》1992,38(1):359-396
Central to the Model Management (MM) function is the creation and maintenance of a knowledge-based model repository. The Model Knowledge Base (MKB) provides the basis by which information about models can be shared to facilitate consistent and controlled utilization of existing models for decision making, as well as the development of new models. Various schemes for representing individual models have been proposed in the literature. This paper focuses on how best to structure, control, and administer a large MKB to support organization-wide modeling activities. Guided by a recently proposed systems framework for MM, we describe a number of concepts which are useful for capturing the semantics and structural relationships of models in an MKB. These concepts, and the nature of the MMS functions to be supported, are then used to derive specific information management requirements for model bases. Four major requirements are identified: (1) management of composite model configurations; (2) management of model version histories; (3) support for the model consultation and selection functions of an MMS; and (4) support for multiple logical MKBs (private, group, and public). We argue that traditional record-based approaches to data management appear to fall short of capturing the rich semantics present in an MM environment. The paper proposes an architecture for an MMS, focusing on its major component — the MKB Management Subsystem. An implementation of this architecture is briefly described. 相似文献
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产业关联分析动态网络模型 总被引:1,自引:0,他引:1
投入产出关联效应分析模型应用完全经济关联关系的概念,较为全面的反映了产业部门间的关联关系.然而,传统的投入产出关联效应分析对产业部门间的关联关系做了简化处理,并没有考虑经济活动的传导时滞因素所产生的动态影响,这种处理方式使模型的应用受到较多限制.利用有向加权网络工具,考虑经济活动的传导时滞,构建了产业关联分析动态网络模型.该模型与传统投入产出模型相比具有以下三个特点:一是考虑了产业部门间及部门内部传导时滞的作用,对部门间关联效应及传导过程作了动态描述,使其关联关系更加符合实际;二是可计算任意时点上一个部门产量的变化对系统中各部门关联效应的大小;三是该模型经济含义直观,易于理解,且易于利用计算机仿真模拟. 相似文献
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The paper analyzes the theory and application of Markowitz Mean-Variance Model and CAPM model. Firstly, it explains the development process and standpoints of two models and deduces the whole process in detail. Then 30 stocks are choosen from Shangzheng 50 stocks and are testified whether the prices of Shanghai stocks conform to the two models. With the technique of time series and panel data analysis, the research on the stock risk and effective portfolio by ORIGIN and MATLAB software is conducted. The result shows that Shanghai stock market conforms to Markowitz Mean-Variance Model to a certain extent and can give investors reliable suggestion to gain higher return, but there is no positive relation between system risk and profit ratio and CAPM doesn't function well in China's security market. 相似文献
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皮尔曲线模型的推广及其应用 总被引:4,自引:0,他引:4
叶宗裕 《数学的实践与认识》2004,34(7):72-76
在分析皮尔曲线模型增长特性的基础上 ,提出了 1 4种推广模型 ,并依据这些模型建立了几种主要耐用消费品拥有量的预测模型 .预测模型的精度很高 相似文献
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Andrew Hoegh Dipayan Maiti Scotland Leman 《Journal of computational and graphical statistics》2018,27(2):436-448
Model selection algorithms are required to efficiently traverse the space of models. In problems with high-dimensional and possibly correlated covariates, efficient exploration of the model space becomes a challenge. To overcome this, a multiset is placed on the model space to enable efficient exploration of multiple model modes with minimal tuning. The multiset model selection (MSMS) framework is based on independent priors for the parameters and model indicators on variables. Posterior model probabilities can be easily obtained from multiset averaged posterior model probabilities in MSMS. The effectiveness of MSMS is demonstrated for linear and generalized linear models. Supplementary material for this article is available online. 相似文献