“每事务于宽厚”的汉章帝

“每事务于宽厚”的汉章帝曹金华汉章帝刘但，是东汉第三代继世令主，也是以＊宽厚长者”著称的封建帝王。在他统治时期，曾一反光武、明帝之“严切”政治，实行了“每事务于宽厚”①的政策。虽然其在位仅十三年，但这一政策却对东汉政权产生了重大而深远的影响。因此颇有...     

用Powell法求颗粒尺寸分布

本文用最优化理论中的Powell直接法求激光粒度仪中的颗粒尺寸分布。数值模拟及对标准颗粒的实测表明,该算法的计算精度高,能较好地解决粒度仪通常存在的计算结果随初始设定值变化的多值性问题。     

Exact sample size determination in a weibull test plan when there is time censoring

Engineers who conduct reliability tests need to choose the sample size when designing a test plan. The model parameters and quantiles are the typical quantities of interest. The large-sample procedure relies on the property that the distribution of the t -like quantities is close to the standard normal in large samples. In this paper, we use a new procedure based on both simulation and asymptotic theory to determine the sample size for a test plan. Unlike the complete data case, the t -like quantities are not pivotal quantities in general when data are time censored. However we show that the distribution of the t -like quantities only depend on the expected proportion failing and obtain the distributions by simulation for both complete and time censoring case when data follow Weibull distribution. We find that the large-sample procedure usually underestimates the sample size even when it is said to be 200 or more. The sample size given by the proposed procedure insures the requested nominal accuracy and confidence of the estimation when the test plan results in complete or time censored data. Some useful figures displaying the required sample size for the new procedure are also presented.     

A revisit to test the equality of variances of several populations

We revisit the problem of testing homoscedasticity (or, equality of variances) of several normal populations which has applications in many statistical analyses, including design of experiments. The standard text books and widely used statistical packages propose a few popular tests including Bartlett's test, Levene's test and a few adjustments of the latter. Apparently, the popularity of these tests have been based on limited simulation study carried out a few decades ago. The traditional tests, including the classical likelihood ratio test (LRT), are asymptotic in nature, and hence do not perform well for small sample sizes. In this paper we propose a simple parametric bootstrap (PB) modification of the LRT, and compare it against the other popular tests as well as their PB versions in terms of size and power. Our comprehensive simulation study bursts some popularly held myths about the commonly used tests and sheds some new light on this important problem. Though most popular statistical software/packages suggest using Bartlette's test, Levene's test, or modified Levene's test among a few others, our extensive simulation study, carried out under both the normal model as well as several non-normal models clearly shows that a PB version of the modified Levene's test (which does not use the F-distribution cut-off point as its critical value), and Loh's exact test are the “best” performers in terms of overall size as well as power.     

中国制造业企业创新行为的观测和实证研究 ——基于浙江省制造业1454家企业问卷调查的分析

 本文在浙江省制造业1454家企业大样本调查问卷的基础上,在微观层面研究了企业创新行为以及影响因素。首先利用统计分析的方法考察了企业创新投入的特征、创新投入的行业分布以及创新投入的产出绩效,并且发现了企业规模与R&;D强度之间呈现倒U型关系,这与安同良等人发现的倾斜V型关系的结论不同。其次运用计量分析的方法在有效控制了企业所处行业的技术水平差异、企业产权结构、政府资金扶持、企业品牌和企业设备技术水平后,研究发现：企业规模与企业创新投入之间也呈现较明显的倒U型关系,并且存在规模“拐点”;企业知识产权战略对企业创新投入具有明显的促进作用;出口贸易对企业创新投入并不显著,但发达国家特别是针对发展中国家设置的技术性贸易壁垒的技术标准化要求对企业创新投入有比较明显的促进作用;而企业集聚对企业的创新投入的影响并不确定。     

Accelerated test system strength models based on Birnbaum–Saunders distribution: a complete Bayesian analysis and comparison

Several models for studies related to tensile strength of materials are proposed in the literature where the size or length component has been taken to be an important factor for studying the specimens’ failure behaviour. An important model, developed on the basis of cumulative damage approach, is the three-parameter extension of the Birnbaum–Saunders fatigue model that incorporates size of the specimen as an additional variable. This model is a strong competitor of the commonly used Weibull model and stands better than the traditional models, which do not incorporate the size effect. The paper considers two such cumulative damage models, checks their compatibility with a real dataset, compares them with some of the recent toolkits, and finally recommends a model, which appears an appropriate one. Throughout the study is Bayesian based on Markov chain Monte Carlo simulation.     

独生子女规模估算及其对政府奖励性支出的影响——以苏州市为例

本文将抽样调查资料与人口普查资料相结合,利用多种统计方法、多方案推算苏州市独生子女存量规模以及未来各年数量,并据此测算了未来各年政府可能的配套奖励性支出。研究结果表明：独生子女大规模进入婚育年龄将势必引起政策生育率的上升,未来各年政府用于独生子女家庭及其父母养老等计划生育政策奖励性支出将逐年增加．财政负担日益加重。建议政府对计划生育配套奖励政策适时进行调整,由现行的提供物质奖励向提供优质服务和社会保障转变。     

MODELING THE LIFETIME OF LONGITUDINAL ELEMENTS

In the study of the stochastic behaviour of the lifetime of an element as a function of its length, it is often observed that the failure time (or lifetime) decreases as the length increases. In probabilistic terms, such an idea can be expressed as follows. Let T be the lifetime of a specimen of length x, so the survival function, which denotes the probability that an element of length x survives till time t, will be given by S_T (t, x) = P(T > t/α(x), where α(x) is a monotonically decreasing function. In particular, it is often assumed that T has a Weibull distribution. In this paper, we propose a generalization of this Weibull model by assuming that the distribution of T is Generalized gamma (GG). Since the GG model contains the Weibull, Gamma and Lognormal models as special and limiting cases, a GG regression model is an appropriate tool for describing the size effect on the lifetime and for selecting among the embedded models. Maximum likelihood estimates are obtained for the GG regression model with α(x) = cx^b . As a special case this provide an alternative to the usual approach to estimation for the GG distribution which involves reparametrization. Related parametric inference issues are addressed and illustrated using two experimental data sets. Some discussion of censored data is also provided.     

Optimal estimation of a finite population mean under generalized random permutation models

Employing certain generalized random permutation models and a general class of linear estimators of a finite population mean, it is shown that many of the conventional estimators are “optimal” in the sense of minimum average mean square error. Simple proofs are provided by using a well-known theorem on UMV estimation. The results also cover certain simple response error situations.     

近代日本消费需求变动的因素分析

长期影响近代日本消费需求变动的因素主要有四个方面:国民经济的不断增长和国民收入的不断提高是近代日本消费需求逐渐上升的物质基础和前提条件;近代工矿交通事业的发展,使国民收入分配格局朝着有利于劳动的方向转变,这是促进近代日本消费需求不断上升的积极力量;人口规模及其构成的变动是近代日本消费需求不断上升的重要推动力量;消费的示范效应、攀比行为和不可逆行为对消费需求不断上升起着一定的推动作用。