A stochastic approximation algorithm for maximum-likelihood estimation with incomplete data

We propose a new stochastic approximation (SA) algorithm for maximum-likelihood estimation (MLE) in the incomplete-data setting. This algorithm is most useful for problems when the EM algorithm is not possible due to an intractable E-step or M-step. Compared to other algorithm that have been proposed for intractable EM problems, such as the MCEM algorithm of Wei and Tanner (1990), our proposed algorithm appears more generally applicable and efficient. The approach we adopt is inspired by the Robbins-Monro (1951) stochastic approximation procedure, and we show that the proposed algorithm can be used to solve some of the long-standing problems in computing an MLE with incomplete data. We prove that in general O(n) simulation steps are required in computing the MLE with the SA algorithm and O(n log n) simulation steps are required in computing the MLE using the MCEM and/or the MCNR algorithm, where n is the sample size of the observations. Examples include computing the MLE in the nonlinear error-in-variable model and nonlinear regression model with random effects.     

A new class of measurement-error models,with applications to dietary data

Measurement-error modelling occurs when one cannot observe a covariate, but instead has possibly replicated surrogate versions of this covariate measured with error. The vast majority of the literature in measurement-error modelling assumes (typically with good reason) that given the value of the true but unobserved (latent) covariate, the replicated surrogates are unbiased for latent covariate and conditionally independent. In the area of nutritional epidemiology, there is some evidence from biomarker studies that this simple conditional independence model may break down due to two causes: (a) systematic biases depending on a person's body mass index, and (b) an additional random component of bias, so that the error structure is the same as a one-way random-effects model. We investigate this problem in the context of (1) estimating distribution of usual nutrient intake, (2) estimating the correlation between a nutrient instrument and usual nutrient intake, and (3) estimating the true relative risk from an estimated relative risk using the error-prone covariate. While systematic bias due to body mass index appears to have little effect, the additional random effect in the variance structure is shown to have a potentially important effect on overall results, both on corrections for relative risk estimates and in estimating the distribution of usual nutrient intake. However, the effect of dietary measurement error on both factors is shown via examples to depend strongly on the data set being used. Indeed, one of our data sets suggests that dietary measurement error may be masking a strong risk of fat on breast cancer, while for a second data set this masking is not so clear. Until further understanding of dietary measurement is available, measurement-error corrections must be done on a study-specific basis, sensitivity analyses should be conducted, and even then results of nutritional epidemiology studies relating diet to disease risk should be interpreted cautiously.     

Least squares estimation of varying‐coefficient hazard regression with application to breast cancer dose‐intensity data

To enhance modeling flexibility, the authors propose a nonparametric hazard regression model, for which the ordinary and weighted least squares estimation and inference procedures are studied. The proposed model does not assume any parametric specifications on the covariate effects, which is suitable for exploring the nonlinear interactions between covariates, time and some exposure variable. The authors propose the local ordinary and weighted least squares estimators for the varying‐coefficient functions and establish the corresponding asymptotic normality properties. Simulation studies are conducted to empirically examine the finite‐sample performance of the new methods, and a real data example from a recent breast cancer study is used as an illustration. The Canadian Journal of Statistics 37: 659–674; 2009 © 2009 Statistical Society of Canada     

Nonparametric estimating equations based on a penalized information criterion

It has recently been observed that, given the mean‐variance relation, one can improve on the accuracy of the quasi‐likelihood estimator by the adaptive estimator based on the estimation of the higher moments. The estimation of such moments is usually unstable, however, and consequently only for large samples does the improvement become evident. The author proposes a nonparametric estimating equation that does not depend on the estimation of such moments, but instead on the penalized minimization of asymptotic variance. His method provides a strong improvement over the quasi‐likelihood estimator and the adaptive estimators, for a wide range of sample sizes.     

On diagnostic checking of the autoregressive conditional intensity model

The autoregressive conditional intensity model proposed by Russell (1998) is a promising option for fitting multivariate high frequency irregularly spaced data. The authors acknowledge the validity of this model by showing the independence of its generalized residuals, a crucial assumption of the model formulation not readily recognized by researchers. The authors derive the large‐sample distribution of the autocorrelations of the generalized residual series and use it to construct a goodness‐of‐fit test for the model. Empirical results compare the performance of their test with other off‐the‐shelf tests such as the Ljung–Box test. They illustrate the use of their test with transaction records of the HSBC stock.     

Long maternal working hours were linked to obesity,underweight and stunting in children under age 5 in China

This study assessed the relationship between maternal working hours and stunting, underweight and obesity in children under age 5 in China, using data from the China Nutrition and Health Survey (CNHS) conducted in 2002 and multivariable logistic regression. We found that maternal work hours 25–40 or >40 h per week were associated with a higher risk for underweight and stunting (under growth) in children under age 5. The association between working 25–40 h per week and stunting was somewhat stronger for children from low-income families and the effect of working >40 h per week on underweight was larger among children from mothers with lower education, although with marginal significance (90% confidence). In contrast, we found that long maternal work hours (>40 h per week) were associated with a lower risk for overweight and obesity in children under age 5. This association was stronger among children from mothers with lower education.     

论国有企业出资人财务监督的方式

为了加强国企的财务监督,各级政府采取了会计人员委派制、财务总监制或稽查特派员制.比较分析这三种财务监督的方式可见,会计人员委派制只适用于非企业单位和机关;稽查特派员制适用于对大型重点国有企业的监督;财务总监制适用于所有国有企业,但必须明确财务总监的委派权力属于企业的董事会,代表的是国有资本所有者,不是政府.所以,委派财务总监不是政府行为,而是企业行为.     

The “Absence” of Asian Regional Economic Integration and the Development Orientation of the Belt and Road

Asia has a special significance in China’s neighborhood strategy. Geographically, the Belt and Road Initiative faces the countries of Asia or China’s neighbors in the first place. Asia is clearly marked by an imbalance in and “absence” of regional economic integration. This “absence” is two-fold: it is expressed on the one hand as a lack of unified institutional arrangements for regional economic integration, and on the other as the inability of underdeveloped countries in the region to truly participate in regional economic integration and thereby gain opportunities for development. Compared with the rule-oriented nature of existing regional economic integration mechanisms, the Belt and Road Initiative, as a new type of regional cooperation mechanism, displays an orientation towards development. All existing regional economic integration arrangements, regardless of their form, establish specific rules on access thresholds, the rights and duties of member countries, schedules and roadmaps, dispute resolution mechanisms and so forth. This is not the case for the Belt and Road, which is not predicated on specific rules, but establishes its overall framework by orienting itself towards development. Overall, the development orientation of the Belt and Road is helpful not only in overcoming the inherent defects of Asian regional economic integration, but in responding to the new challenge of anti-globalization. This is an institutional public good that China offers to Asia and to the world.     

我们是怎样编写《辽宁期刊史》的

从2005年开始,辽宁省新闻出版局、辽宁省期刊协会共同决定编撰一套“辽宁期刊史书系”,含括《辽宁老期刊图录》、《辽宁期刊史》、《辽宁当代刊社史选编》、《辽宁当代期刊人传略》等四部书。其中以《辽宁期刊史》为书系的主体和核心。辽宁的期刊编史工作从一开始就是在中国期刊协会指导下进行的。对于大纲的编制,书稿的审定,以及编写过程中有关难题的处理,中国期刊协会的现任会长石峰和前任会长张伯海,都给予了具体指导并提出了宝贵的意见。     

两小时高速惬意行

桓仁是个好地方。10年前曾在五女山、桓龙湖流连多日,一度被那里的美景吸引,乐而忘家。此后多次有过再游桓仁的念头,但一想到那崎岖漫长的山路,快速便捷的旅游目的地便战了出行的首选。2012年的国庆节前夕,直通桓仁的高速公路建成通车。十一期间,前往桓仁的游客比去年多了4倍。10月12日,黄金周刚过的第一个