An Exploratory Study of Variations in Exposure to Environmental Tobacco Smoke in the United States

There is considerable interest in assessing exposure to environmental tobacco smoke (ETS) and in understanding the factors that affect exposure at various venues. The impact of these complex factors can be researched only if monitoring studies are carefully designed. Prior work by Jenkins et al. gathered personal monitor and diary data from 1,564 nonsmokers in 16 metropolitan areas of the United States and compared workplace exposures to ETS with exposures away from work. In this study, these data were probed further to examine (1) the correspondence between work and away-from-work exposure concentrations of ETS; (2) the variability in exposure concentration levels across cities; and (3) the association of ETS exposure concentrations with select socioeconomic, occupation, and lifestyle variables. The results indicate (1) at the population level, there was a positive association between ETS concentrations at the work and away-from-work environments; (2) exposure concentration levels across the 16 cities under consideration were highly variable; and (3) exposure concentration levels were significantly associated with occupation, education, household income, age, and dietary factors. Workplace smoking restrictions were associated with low ETS concentration levels at work as well as away from work. Generally, the same cities that exhibited either lower or higher away-from-work exposure concentration levels also showed lower or higher work exposure concentration levels. The observations suggest that similar avoidance characteristics as well as socioeconomic and other lifestyle factors that affect exposure to ETS may have been in operation in both away-from-work and work settings.     

Semiparametric smoothing of sparse contingency tables

In the paper simple resampling technique based on semiparametric smoothing is introduced. Although the method is very flexible and in principle can be applied to any sparse data and ill-posed statistical problem, its efficient or even reasonable implementation requires special investigation. In the paper a problem of fitting local dependence structure of finite-state random sequences is addressed. This problem is relevant, for example, in genetics, bioinformatics, computer linguistics, etc., and usually leads to analysis of sparse contingency tables of dependent categorical data. Thus, the classical assumptions of log-linear model, a standard technique for analysis of contingency tables, do not hold. A framework convenient for implementation of semiparametric smoothing and resampling is proposed. It is based on a special representation form of data under consideration and generalized logit model. A computer experiment is carried out to gain better insight on practical performance of the procedure.     

BL Lac天体红外谱性质(英文)

对所收集的ＢＬ Ｌａｃ天体的红外资料（Ｆａｎ＆　Ｌｉｎ １９９９）进行讨论，发现具有红移的 ２７个 ＢＬ Ｌａｃ天体的红外谱指数与红移之间有强相关，这种强相关也许意味着谱存在演化效应。     

单因子利率期限结构模型的实证检验

本文运用GMM方法对单因素利率期限结构模型进行了估计,考虑到设定的模型以及无论用哪种方法估计出来的参数值均不能完全描述利率的动态特征,我们在利率期限结构模型中加入残差项来反应不能由设定模型所描述的那部分信息;并首次运用Bootstrap方法对参数估计值的准确度进行了分析,发现两种方法得到的结果存在着显著性差异,置信区间没有公共部分,即参数的真值基本上不可能相同。     

Inflation and the Divergence of Relative Prices: Evidence from a Cointegration Analysis

The relation between inflation and RPV plays a prominent role in explaining the costs of inflation. This study investigates whether the CPI subcategories drift apart more over a period of high inflation rates than during one of low inflation. The wider dispersion of the subcategories is reflected in an increasing number of common stochastic trends in the system of sub price indices. The results for US data as well as for cross-country comparisons indicate that the influence of inflation on the dispersion of relative prices cannot be revealed by counting cointegrating relations. Thus, the number of stochastic trends or cointegrating relations is not a reliable indicator for the distorting effect of inflation on the dispersion of relative prices.     

英语素质教育的几个指导原则

高等教育正经历着重大的变革，英语作为高等教育中不可缺少的组成部分，日益成为跨世纪人才的基本素质之一。因此素质教育成了摆在广大英语工作者面前的一项艰巨任务。英语由应试教育向素质教育转变，教师素质的提高是关键。     

Attenuation of treatment effect due to measurement variability in assessment of progression-free survival

For normally distributed data analyzed with linear models, it is well known that measurement error on an independent variable leads to attenuation of the effect of the independent variable on the dependent variable. However, for time‐to‐event variables such as progression‐free survival (PFS), the effect of the measurement variability in the underlying measurements defining the event is less well understood. We conducted a simulation study to evaluate the impact of measurement variability in tumor assessment on the treatment effect hazard ratio for PFS and on the median PFS time, for different tumor assessment frequencies. Our results show that scan measurement variability can cause attenuation of the treatment effect (i.e. the hazard ratio is closer to one) and that the extent of attenuation may be increased with more frequent scan assessments. This attenuation leads to inflation of the type II error. Therefore, scan measurement variability should be minimized as far as possible in order to reveal a treatment effect that is closest to the truth. In disease settings where the measurement variability is shown to be large, consideration may be given to inflating the sample size of the study to maintain statistical power. Copyright © 2012 John Wiley & Sons, Ltd.     

Wavelet-based confidence intervals for the self-similarity parameter

We propose and compare several methods of constructing wavelet-based confidence intervals for the self-similarity parameter in heavy-tailed observations. We use empirical coverage probabilities to assess the procedures by applying them to Linear Fractional Stable Motion with many choices of parameters. We find that the asymptotic confidence intervals provide empirical coverage often much lower than nominal. We recommend the use of resampling confidence intervals. We also propose a procedure for monitoring the constancy of the self-similarity parameter and apply it to Ethernet data sets.     

Interval estimation of the mean in a two-stage nested model

The problem of constructing confidence intervals to estimate the mean in a two-stage nested model is considered. Several approximate intervals, which are based on both linear and nonlinear estimators of the mean are investigated. In particular, the method of bootstrap is used to correct the bias in the ‘usual’ variance of the nonlinear estimators. It is found that the intervals based on the nonlinear estimators did not achieve the nominal confidence coefficient for designs involving a small number of groups. Further, it turns out that the intervals are generally conservative, especially at small values of the intraclass correlation coefficient, and that the intervals based on the nonlinear estimators are more conservative than those based on the linear estimators. Compared with the others, the intervals based on the unweighted mean of the group means performed well in terms of coverage and length. For small values of the intraclass correlation coefficient, the ANOVA estimators of the variance components are recommended, otherwise the unweighted means estimator of the between groups variance component should be used. If one is fortunate enough to have control over the design, he is advised to increase the number of groups, as opposed to increasing group sizes, while avoiding groups of size one or two.     

基本面因素与人民币均衡汇率

测算方法的差异使得对人民币均衡汇率水平的不同研究的测度结果大相径庭。本文借鉴新近研究,引入生产率和国外净资产变量,采用经常账户缺口法、基本行为均衡方法的误差修正模型和ML-ARCH模型测度了人民币汇率的均衡区间;并探讨了决定均衡汇率变化的基本面因素。结果证实人民币被低估的水平并不十分显著,生产率的提升、贸易条件变化和增长导向的经济发展模式和外汇储备是决定均衡汇率变化趋势的关键基本面因素;均衡汇率变化的估值效应能够显著影响国外净资产水平。