Accelerated life regression modelling of dependent bivariate time‐to‐event data

To analyze bivariate time‐to‐event data from matched or naturally paired study designs, researchers frequently use a random effect called frailty to model the dependence between within‐pair response measurements. The authors propose a computational framework for fitting dependent bivariate time‐to‐event data that combines frailty distributions and accelerated life regression models. In this framework users can choose from several parametric options for frailties, as well as the conditional distributions for within‐pair responses. The authors illustrate the flexibility that their framework represents using paired data from a study of laser photocoagulation therapy for retinopathy in diabetic patients.     

Interest rate policies and inflation in interdependent economies: Recent policy dilemmas

This paper examines Federal Reserve Board policies that are premised on a negative short-run association of interest rate movements and the rate of inflation. In particular, econometric evidence is provided, supporting the view that tighter monetary policy appears to raise inflation rates in the short run. Conversely, it is demonstrated that easier monetary policy does not necessarily raise inflation rates in the short run. In the case of uncoordinated monetary restrictiveness, interest rate competition among major countries can produce higher inflation and lower growth than was originally intended.     

Distribution system choice in a service industry: An analysis of international insurance firms operating in the United States

Service firms play an increasingly important role in the global economy. However, the internationalization strategies of such firms, and especially their distribution system choices, have been underexplored in the international management literature. One specific service industry that has internationalized rapidly in recent years is the insurance industry. This paper examines the determinants and performance implications of the choice by international insurance firms between two rival distribution systems: direct writing and independent sales agents. Drawing on the transaction cost theory-based literature on resource commitment, control, and risk, we develop hypotheses on the determinants of the choice between these two distribution systems and on the performance implications of this choice for insurance firms. Analyzing a sample of 168 distribution entries into the United States by insurance firms from six foreign countries over the 1992–2000 period, we find that cultural distance has a U-shaped effect on the probability of direct writing, and that an insurer's intangible assets have a positive effect on this probability. We also find that the direct writing system performs better in terms of profitability, but that the independent agency system performs better in terms of market share growth.     

Analyzing Evacuation Versus Shelter‐in‐Place Strategies After a Terrorist Nuclear Detonation

We superimpose a radiation fallout model onto a traffic flow model to assess the evacuation versus shelter‐in‐place decisions after the daytime ground‐level detonation of a 10‐kt improvised nuclear device in Washington, DC. In our model, ≈80k people are killed by the prompt effects of blast, burn, and radiation. Of the ≈360k survivors without access to a vehicle, 42.6k would die if they immediately self‐evacuated on foot. Sheltering above ground would save several thousand of these lives and sheltering in a basement (or near the middle of a large building) would save of them. Among survivors of the prompt effects with access to a vehicle, the number of deaths depends on the fraction of people who shelter in a basement rather than self‐evacuate in their vehicle: 23.1k people die if 90% shelter in a basement and 54.6k die if 10% shelter. Sheltering above ground saves approximately half as many lives as sheltering in a basement. The details related to delayed (i.e., organized) evacuation, search and rescue, decontamination, and situational awareness (via, e.g., telecommunications) have very little impact on the number of casualties. Although antibiotics and transfusion support have the potential to save ≈10k lives (and the number of lives saved from medical care increases with the fraction of people who shelter in basements), the logistical challenge appears to be well beyond current response capabilities. Taken together, our results suggest that the government should initiate an aggressive outreach program to educate citizens and the private sector about the importance of sheltering in place in a basement for at least 12 hours after a terrorist nuclear detonation.     

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.