Parameter Estimation Robust to Low-Frequency Contamination

We provide methods to robustly estimate the parameters of stationary ergodic short-memory time series models in the potential presence of additive low-frequency contamination. The types of contamination covered include level shifts (changes in mean) and monotone or smooth time trends, both of which have been shown to bias parameter estimates toward regions of persistence in a variety of contexts. The estimators presented here minimize trimmed frequency domain quasi-maximum likelihood (FDQML) objective functions without requiring specification of the low-frequency contaminating component. When proper sample size-dependent trimmings are used, the FDQML estimators are consistent and asymptotically normal, asymptotically eliminating the presence of any spurious persistence. These asymptotic results also hold in the absence of additive low-frequency contamination, enabling the practitioner to robustly estimate model parameters without prior knowledge of whether contamination is present. Popular time series models that fit into the framework of this article include autoregressive moving average (ARMA), stochastic volatility, generalized autoregressive conditional heteroscedasticity (GARCH), and autoregressive conditional heteroscedasticity (ARCH) models. We explore the finite sample properties of the trimmed FDQML estimators of the parameters of some of these models, providing practical guidance on trimming choice. Empirical estimation results suggest that a large portion of the apparent persistence in certain volatility time series may indeed be spurious. Supplementary materials for this article are available online.     

Local power of panel unit root tests allowing for structural breaks

The asymptotic local power of least squares–based fixed-T panel unit root tests allowing for a structural break in their individual effects and/or incidental trends of the AR(1) panel data model is studied. Limiting distributions of these tests are derived under a sequence of local alternatives, and analytic expressions show how their means and variances are functions of the break date and the time dimension of the panel. The considered tests have nontrivial local power in a N^?1/2 neighborhood of unity when the panel data model includes individual intercepts. For panel data models with incidental trends, the power of the tests becomes trivial in this neighborhood. However, this problem does not always appear if the tests allow for serial correlation in the error term and completely vanishes in the presence of cross-section correlation. These results show that fixed-T tests have very different theoretical properties than their large-T counterparts. Monte Carlo experiments demonstrate the usefulness of the asymptotic theory in small samples.     

Two Decades of Stability and Change in Age at First Union Formation

The landscape of union formation has been shifting; Americans are now marrying at the highest ages on record and the majority of young adults have cohabited. Yet little attention has been paid to the timing of cohabitation relative to marriage. Using the National Survey of Families and Households and 4 cycles of the National Survey of Family Growth, the authors examined the timing of marriage, cohabitation, and unions over 20 years. As the median age at first marriage has climbed, the age at cohabitation has remained stable for men and women. The changes in the timing of union formation have been similar according to race/ethnicity. The marked delay in marriage among women and men with low educational attainment has resulted in a near‐convergence in the age at first marriage according to education. The authors conclude that the rise in cohabitation has offset changes in the levels and timing of marriage     

Trends in the age at reproductive transitions in the developing world: The role of education

Girls’ school participation has expanded considerably in the developing world over the last few decades, a phenomenon expected to have substantial consequences for reproductive behaviour. Using Demographic and Health Survey data from 43 countries, this paper examines trends and differentials in the mean ages at three critical life-cycle events for young women: first sexual intercourse, first marriage, and first birth. We measure the extent to which trends in the timing of these events are driven either by the changing educational composition of populations or by changes in behaviour within education groups. Mean ages have risen over time in all regions for all three events, except age at first sex in Latin America and the Caribbean. Results from a decomposition exercise indicate that increases in educational attainment, rather than trends within education groups, are primarily responsible for the overall trends. Possible explanations for these findings are discussed.     

Extending the pursuit of flow (lean) management to encompass sales,general and administrative functions

Abstract

Operations management tends to be treated independent of other business functions—the silo syndrome. In this article, we call for operations management (OM) to broaden its perspective by strengthening linkages with other functions of the business, thereby to realize competitive advantages and strategic integration, as well as to avoid resource misallocation. The issues involved are presented and tested by examining the effects of intermeshing sales, general and administrative (SG&A) expenditures with customer-centred flow manufacturing, the latter being measured by system inventory as surrogate for customer lead time. In doing so, we designate trends in total inventory as the independent variable—representative of a dominant target of flow/lean management—and trends in SG&A expenditures as the output variable. The research tasks are enabled by inventory and SG&A data being widely available in companies’ audited financial statements. Such hard data offers methodological and validation advantages over, say, opinion-based survey research. The research adds bulk to existing flow/lean management theory and can be helpful in inducing primary business functions (e.g. OM, finance, sales and marketing) and sub-functions (such as SG&A and management accounting) to engage in cross-functional efforts in the cause of flow-oriented process improvement and company competitiveness.     

Alternative diff-in-diffs estimators with several pretreatment periods

This paper deals with the identification of treatment effects using difference-in-differences estimators when several pretreatment periods are available. We define a family of identifying nonnested assumptions that lead to alternative difference-in-differences estimators. We show that the most usual difference-in-differences estimators imply equivalence conditions for the identifying nonnested assumptions. We further propose a model that can be used to test multiple equivalence conditions without imposing any of them. We conduct a Monte Carlo analysis and apply our approach to several recent papers to show its practical relevance.     

辽宁利用外商直接投资的变化趋势、业绩与对策

着重分析20多年来辽宁省在利用外商直接投资方面的总量变化和结构变化,以及利用外商直接投资的业绩,最后提出辽宁进一步扩大利用外商直接投资的对策。     

关于中国电影史研究的若干问题之思考

在中国电影史的研究过程中,要注重把中国现代电影史的研究和中国当代电影史的研究打通,即对一百多年来中国电影的发展和演变进行全面、系统的梳理与研究,深入探讨在此过程中形成的优良传统、积累的成功经验和应该汲取的主要教训,认真总结其创作生产的基本规律。其次,既要加强中国电影通史的研究,又要加强各类断代史、专门史、区域史和口述史的研究,从而使中国电影史的研究更加丰富、全面。另外,还要进一步加强域外各种文艺思潮、文艺流派和各种电影思潮、电影流派对中国电影发展之影响的研究,以及中国传统文化对中国电影发展之影响的研究。     

增强社会主义核心价值体系引领力探析

增强社会主义核心价值体系引领力,提高引领水平,充分发挥核心价值体系对当代社会思潮的巨大引擎作用,是理论和实践的双重要求。社会主义核心价值体系引领力具体化为马克思主义的指导力、共同理想的凝聚力、民族精神和时代精神的鼓舞力以及社会主义荣辱观的感化力。增强社会主义核心价值体系引领力在遵循唯物辩证原则的基础上,需要从全局中找准引领的着力点,注重人文关怀、社会规范引领以及引导群众自我教育和自觉践履,以切实提高引领的实效性。力图弥补当前学术界、理论界在社会主义核心价值体系引领问题上的研究缺陷,成为本文研究的动力,并以此就教于学界同仁。     

贵州省生态文明城市建设发展态势思考

生态文明城市发展已成为贵州区域发展的重要组成部分。探索生态文明城市建设的发展趋势,具有十分重要的意义。对于贵州这样的后发展地区来说,关键是要从低碳经济、绿色发展、生态文明三个方面取得突破。本文从经济环境、生态环境、法治环境、居住环境和人文环境五个方面的有机互动出发,研究并分析构建贵州生态文明城市建设的发展目标体系,提出贵州生态文明城市建设的三个发展态势与发展道路：低碳经济的工业化道路、绿色发展的可持续道路和生态文明的城市化道路。