Multi-scale tests for serial correlation

This paper introduces a new family of portmanteau tests for serial correlation. Using the wavelet transform, we decompose the variance of the underlying process into the variance of its low frequency and of its high frequency components and we design a variance ratio test of no serial correlation in the presence of dependence. Such decomposition can be carried out iteratively, each wavelet filter leading to a rich family of tests whose joint limiting null distribution is a multivariate normal. We illustrate the size and power properties of the proposed tests through Monte Carlo simulations.     

Experience,Learning, and Returns to Scale

The experience curve is a tool for forecasting future decreases in average cost as a function of cumulative output/volume. The extent of an experience effect has profound implications for both pricing strategy and the focus on market share as a managerial objective. At the same time, the underlying sources of the experience effect are not well understood. This article demonstrates that, as commonly measured, experience effects are aggregated with the effects of increasing returns to scale. This implies that standard experience curve estimates are misspecified because they suffer from an omitted variable bias. Strategic implications of the experience‐scale link are discussed.     

SVHC第23批新增4项物质测试方法研究

本文建立了同时测定欧盟高关注物质(SVHC)第23批新增的4种物质[1-乙烯基咪唑、-甲基咪唑、4-羟基苯甲酸丁酯、双(乙酰丙酮酸)二丁基锡的气相色谱质谱联用仪(GC-MS)]的检测方法。将样品用二氯甲烷超声后,采用选择离子监控模式(SIM)进行分析样品中的待测物。实验结果表明,4种物质在50 mg/L范围内线性关系良好,线性相关系数为0.995以上;样品加标回收率为94%110%,相对标准偏差(RSD)小于7%;方法检出限分别为2 mg/kg、10mg/kg、0.8 mg/kg、0.6 mg/kg,解决了欧盟新增加的4种SVHC测试问题。     

Comparative persistence and adherence with newer anti-hyperglycemic agents to treat patients with type 2 diabetes in the United States

Objectives: Non-adherence and non-persistence to anti-hyperglycemic agents are associated with worse clinical and economic outcomes in patients with type 2 diabetes. This study evaluated treatment persistence and adherence across newer anti-hyperglycemic agents (canagliflozin, dapagliflozin, sitagliptin, saxagliptin, linagliptin, liraglutide, or exenatide).

Methods: This retrospective cohort study of Truven Health Analytics Marketscan databases included adult patients with type 2 diabetes whose first pharmacy claim for a newer anti-hyperglycemic agent was between February 1, 2014 and July 31, 2014. Treatment persistence and adherence were assessed for 12 months after the first claim (post-index). Persistence was defined as no gap ≥90 days between the end of one pharmacy claim and the start of the next pharmacy claim post-index. Adherence used two definitions: proportion of days covered (PDC) and medication possession ratio (MPR). Multivariable analyses of non-persistence (hazard ratios) and adherence (odds ratios) were adjusted for baseline demographics, drug cost, clinical characteristics, and other anti-hyperglycemic agents.

Results: A total of 11,961 patients met all study selection criteria. Persistence rates at 12 months were significantly greater (p?p?=?0.83; PDC?=?0.79) and canagliflozin 300?mg (MPR?=?0.92; PDC?=?0.81) were greater than for the other index anti-hyperglycemic agents (MPR?=?0.33–0.75; PDC?=?0.33–0.72). Consistent results for treatment persistence and adherence were observed in multivariable analyses that were adjusted baseline characteristics.

Conclusions: Canagliflozin was associated with better treatment persistence and treatment adherence compared with other anti-hyperglycemic agents in real-world settings.     

The Global Financial Crises of 2007–2010 and the future of capitalism

This paper presents an analysis of the 2007-2010 Global Financial Crisis which started with the sub-prime crisis in the U.S. and became global very fast. It argues that the financial system in the United States is a complex interlocking structure of markets, institutions and regulators. The causes and culprits of the crisis, the misaligned incentives of participants and exogenous events such as the wars in Afghanistan and Iraq, precipitated failure in key markets: commodities, sub-prime housing, equities, and credit. One of the strategic consequences of this crisis is that the US will lose its dominance in world power, the frequent crises and vulnerabilities of the Neoliberalism and examines the future of capitalism. Of the alternatives to economic system, the capitalism is the most viable economic system. However, it must adopt real and efficient allocation of resources to maximize welfare of all parties and seriously address the income inequality. It must reject crony capitalism, enact true financial regulation of institutions and markets, end corporate socialism and address the system’s structural deficiencies.     

Revisiting the relationship between suicide and unemployment: Evidence from linear and nonlinear cointegration

This study employs the linear and nonlinear ARDL cointegration methodologies to examine the potential symmetric and asymmetric responses of suicide rates to unemployment rates in the US from 1928 to 2013. Our results suggest that suicide rates are pro-cyclical with respect to the business cycle (measured by changes in the unemployment rate) after extensively controlling for divorce and fertility rates. Unemployment has symmetric long-run effects on the age-adjusted suicide rate and four age-specific (from ages 25–34 to 55–64) suicide rates, while the effect of an economic expansion on suicide rates for those aged over 45 is greater than the effect of an economic recession. These findings imply that the effect of an economic expansion on the decrease of the suicide rate is higher than the effect of an economic recession on the increase of the suicide rate for individuals aged over 45. Therefore, intervention designed to reduce suicidal behaviors should emphasize periods of economic recession more than periods of economic expansion for those of middle age and beyond.     

A decision method for supplier selection in multi-service outsourcing

Although supplier selection in multi-service outsourcing is a very important decision problem, research concerning this issue is still relatively scarce. This paper proposes a decision method for selecting a pool of suppliers for the provision of different service process/product elements. It pioneers the use of collaborative utility between partner firms for supplier selection. A multi-objective model is built to select desired suppliers. This model is proved to be NP-hard, so we develop a multi-objective algorithm based on Tabu search for solving it. We then use an example to show the applicability of the proposed model and algorithm. Extensive computational experiments are also conducted to further test the performance of the proposed algorithm.     

Aggregation of the generalized fractional processes

The paper studies the interaction between aggregation and persistence pertaining to skip sampling of stock variables as well as temporal aggregation of flow variables for the generalized fractional processes. We show that, for skip sampling, the long memory feature at the zero frequency can arise from the aggregation of a generalized fractional series, while temporal aggregation does not induce such phenomenon. Simulation results are included to demonstrate the practical relevance of the theoretical results.     

Oil price shocks and volatility spillovers in the Nigerian sovereign bond market

This paper investigates volatility spillover in the Nigerian sovereign bond market arising from oil price shocks, using Vector Autoregressive Moving Average ‐ Asymmetric Generalized Autoregressive Conditional Heteroscedasticity (VARMA‐AGARCH) model. The paper covers the period March 22, 2011 to April 14, 2016 and makes use of the daily data of the Nigerian Sovereign Bond, Brent oil and West Texas Intermediate (WTI), respectively. We endogenously and sequentially detect structural break points using the test of Bai and Perron (2003) framework. In order to accurately estimate the model, we modify it by incorporating the break points into the VARMA‐AGARCH model, a process which if ignored would lead to model misspecification. The results obtained demonstrate a significant cross‐market volatility transmission between oil and sovereign bond market with ample sensitivity to structural breaks. The study also computes optimum weight portfolio and hedge ratio both with and without structural breaks and results equally indicate sensitivity to structural breaks.