【作者】 高晓明；

【导师】 唐煜；

【作者基本信息】 苏州大学 ， 概率论与数理统计， 2011， 硕士

【摘要】 抽样方法在现实生活中有非常广泛的应用,因此抽样理论得到了统计学者的广泛关注。特别是对于给定密度函数的分布进行抽样,目前已经有多种成熟的方法,如合成法、拒绝法、MCMC方法和分位点方法等。但总体来说,已有文献大多是关于如何实现这些抽样算法的研究,而对于系统比较抽样方法的优劣,目前还没有得到广泛深入的研究。本文基于核密度估计函数概念,首先定义了用来刻画目标函数和样本的核密度估计函数的偏离程度的指标“L_2^-距离”,并以此作为度量样本效果标准,提出了一种采用随机优化算法的抽样方法。最后以一类具有复杂密度函数的分布为例,综合比较了包括合成法、拒绝法、MCMC方法、分位点方法及随机优化等抽样方法的具体表现。通过多次试验抽取不同容量的样本,分析多次试验的L_2^-距离的均值和标准差,同时结合算法运行时间和抽取样本的k阶矩等指标,对抽样的方法进行优劣评价及取舍。计算表明,在处理一维或多维抽样问题时,随机优化算法与其他方法相比,虽然在算法运行上耗时略长,但有很好的稳定性和很高的精度,综合评价具有较明显的优越性。更多还原

【Abstract】 Sampling method has many applications, so sampling theory attracts muchattention in Statistics. Especially, when the probability density function of adistribution is given, there are many existing sampling methods, such as Mixturemethod, Rejection method, MCMC and Quantile method. However, in literature,research is limited to individual descriptions of instructions about algorithms forimplementation of these methods, while systematic comparison among them hasnot been extensively investigated.Based on the concept of kernel density estimation, this paper firstly definesan”L_2^-distance”, which can describe the difference between the probability den-sity function of the distribution and kernel density estimation of a sample. Thenaiming to minimize”L_2^-distance”, a stochastic optimization sampling algorithmis proposed accordingly. Finally, various sampling methods including Mixturemethod, Rejection method, MCMC, Quantile method and Stochastic optimiza-tion methods are compared when a distribution with complex probability densityfunction is considered. Experiments with different sample size are conducted.Means and standard deviations of L_2^-distances are calculated. Time elapsed andk-th moments of different sampling methods are recorded. All results show thatthough a little more time may be need, the stochastic optimization algorithmproposed in the current paper performs better related to stability and accuracy.It generally outperforms other existing sampling methods in comprehensive eval-uation.更多还原