Non-ergodic martingale estimating functions and related asymptotics

Well-known estimation methods such as conditional least squares, quasilikelihood and maximum likelihood (ML) can be unified via a single framework of martingale estimating functions (MEFs). Asymptotic distributions of estimates for ergodic processes use constant norm (e.g. square root of the sample size) for asymptotic normality. For certain non-ergodic-type applications, however, such as explosive autoregression and super-critical branching processes, one needs a random norm in order to get normal limit distributions. In this paper, we are concerned with non-ergodic processes and investigate limit distributions for a broad class of MEFs. Asymptotic optimality (within a certain class of non-ergodic MEFs) of the ML estimate is deduced via establishing a convolution theorem using a random norm. Applications to non-ergodic autoregressive processes, generalized autoregressive conditional heteroscedastic-type processes, and super-critical branching processes are discussed. Asymptotic optimality in terms of the maximum random limiting power regarding large sample tests is briefly discussed.     

Active Ageing Index in Korea – Comparison with China and EU countries

The evidence‐based policymaking relies on the use and robustness of the available data. Many conceptual and operational difficulties restrict this process, not least in making use of evidence to identify policy priorities. The Active Ageing Index (AAI), developed originally for the 28 European Union countries, offers a strong motivation in this respect. This paper reports on the development of the AAI for Korea, a country where speed and level of population aging is among the highest in the world. Drawing on the comparative analysis of the AAI results for Korea, China, and European countries, we find that Korea's AAI (35.3) is higher than the average of the AAI for all EU countries (33.9) but lower than China (37.3). Fitting Korea into the overall ranking with the EU countries and China (ranked 7), Korea is ranked 11, just behind Germany (10). The AAI results in Korea show that the employment domain performs extremely well compared with the EU countries, but other domains, especially “Social participation” and “Independent, healthy and secure living,” are achieving less favorable outcomes. High employment among the current cohorts of older workers in Korea can be attributed largely to the constraints of low pension income status.     

Increasing Returns and Social Contagion in Cultural Industries

A formal definition of cultural industries is developed following four distinct features of cultural goods: (a) oversupply, (b) quality uncertainty, (c) network effects and (d) demand reversal. Drawing on economic and socio-psychological notions of ‘network’, increasing returns and social contagion effects are distinguished. Increasing returns may govern the adoption of standards when choices are binary, social contagion explains the diffusion of cultural goods when choices are multiple. Together, the four structural features delineating cultural industries account for curious competitive dynamics prevalent in cultural markets, such as the notorious 10 : 90 proportionality (under which 10% of cultural goods account for 90% of the market), causal ambiguity about the reasons for success, and the formation of fashions. Six managerial recommendations are advanced, focusing on a criticial circulation point triggering self-sustaining diffusion patterns. Finally ‘project-based enterprises’ and ‘network forms of governance’ are identified as the organizational forms most suited to the dynamics of the cultural markets.     

Penalties and payoffs: The short-term economic consequences of human capital acquisition for resettled refugees in the United States

The relationship between refugee investments in human capital and short-run economic outcomes may influence the extent to which refugees invest in human capital that is associated with positive future economic mobility. Using data from the Annual Survey of Refugees from 2016 and 2017 we assess the relationship between recent investments in human capital and hourly wages for employed refugees in the United States. Results suggest that recent job training has a positive effect on hourly wages. In contrast, enrollment in English classes and educational programmes have no short-term positive effects on hourly wages. When combined with the pressure resettled refugees experience to find employment quickly, these results suggest that the lack of short-term wage benefits from English language or educational courses may dissuade refugees from sufficiently investing in the amount of English language or education necessary to promote positive long-term economic mobility.     

Adaptive designs for IVPT data with mixed scaled average bioequivalence

In vitro permeation tests (IVPT) offer accurate and cost-effective development pathways for locally acting drugs, such as topical dermatological products. For assessment of bioequivalence, the FDA draft guidance on generic acyclovir 5% cream introduces a new experimental design, namely the single-dose, multiple-replicate per treatment group design, as IVPT pivotal study design. We examine the statistical properties of its hypothesis testing method—namely the mixed scaled average bioequivalence (MSABE). Meanwhile, some adaptive design features in clinical trials can help researchers make a decision earlier with fewer subjects or boost power, saving resources, while controlling the impact on family-wise error rate. Therefore, we incorporate MSABE in an adaptive design combining the group sequential design and sample size re-estimation. Simulation studies are conducted to study the passing rates of the proposed methods—both within and outside the average bioequivalence limits. We further consider modifications to the adaptive designs applied for IVPT BE trials, such as Bonferroni's adjustment and conditional power function. Finally, a case study with real data demonstrates the advantages of such adaptive methods.     

Nonresident fathers' parenting, family processes, and children's development in urban, poor, single-mother families

With dramatic growth in nonrmarital births, an increasing number of children are growing up in single-mother families. This study examines the relationships among nonresident fathers' parenting and children's behavioral and cognitive development in low-income, single-mother families. It also considers the personal characteristics of the children's single mothers as well as family processes and economic circumstances. Analyses use the first three waves of longitudinal data from a subsample of single and noncohabiting mothers in the Fragile Families and Child Wellbeing Study. Results suggest that nonresident fathers' parenting is indirectly associated with children's behavior problems and cognitive development. The findings further suggest that those estimated associations are transmitted through mothers' parenting. The study also discusses the policy and practice implications of its findings.     

The representation of North Korean national image in national newspapers in the United States

This study examines how two major U.S. newspapers (The New York Times and The Washington Post) represented North Korea's national image during the two-year period (from 2001 to 2002). According to the findings, The New York Times and Washington Post showed a similar trend in their portrayal of North Korea. An anti-North Korea frame dominated the news coverage of North Korea in both newspapers. Furthermore, this study reveals that most news articles related to North Korea were classified into negative images instead of positive images.     

Immigration and status exchange in Australia and the United States

This paper evaluates the status exchange hypothesis for Australia and the United States, two Anglophone nations with long immigration traditions whose admission regimes place different emphases on skills. Using log-linear methods, we demonstrate that foreign-born spouses trade educational credentials via marriage with natives in both Australian and U.S. marriage markets and, moreover, that nativity is a more salient marriage barrier for men than for women. With some exceptions, immigrant spouses in mixed nativity couples are better educated than native spouses in same nativity couples, but status exchange is more prevalent among the less-educated spouses in both countries. Support for the status exchange hypothesis is somewhat weaker in Australia partly because of lower average levels of education compared with the United States and partly because of the less sharply defined educational hierarchy at the postsecondary level.