Variable markups in the long-run: A generalization of preferences in growth models

This paper introduces variable markups in a horizontal-differentiation growth model by considering a larger class of preferences that nests the classic “CES” specification usually present in the workhorse love-for-variety models. Our first result is to obtain a generalized characterization of the Euler condition for this broader class of utility functions: in our model, the Euler rule features a supplementary term aiming at compensating the consumer for variations in the preference for variety along the consumption level. We are then also able to demonstrate that in our generalized framework, the economy’s balanced growth path displays both endogenous markups and a strictly positive growth rate of the number of available varieties (being the engine of growth). Finally, we show that under endogenous markups, the economy’s growth rate and firms’ market power can display a negative correlation, as opposed to the standard result obtained in the CES framework.     

Effects of degrees of acceptance and awareness on a rate system for lowering mobile bills

South Korea has the highest mobile bills among the OECD countries, and there is strong public demand in the country to reduce expenditure amounts. In response, the South Korean government and mobile carriers have implemented measures such as a “Smart Choice Service,” data-centered plan, and 20% discount scheme in order to reduce mobile bills. However, it is unclear whether these systems have actually led to such a reduction. The present study analyzes quantitatively how people's acceptance and awareness toward rate systems reduce or do not reduce mobile bills, based on the results of a survey conducted here. More specifically, to solve the endogeneity problem of saving behavior's effect on mobile bills, the study adopts the instrumental variables of degree of acceptance and awareness of systems relating to mobile bills. The results show that acceptance and awareness of the system do affect savings behavior and thus mobile bills. If the degree of savings behavior (affected by acceptance and awareness) goes up one step on a seven-point Likert-type scale, there is an average 8.28% savings effect on mobile bills. Thus, this study shows that degrees of acceptance and awareness of the rate system do affect mobile bills.     

Worker search effort as an amplification mechanism

It is well known that the Diamond–Mortensen–Pissarides model exhibits a strong trade-off between cyclical unemployment fluctuations and the size of rents to employment. Introducing endogenous job search effort reduces the strength of the trade-off while bringing the model closer to the data. Ignoring worker search effort leads to a large upward bias in the elasticity of matches with respect to vacancies. Merging the American Time Use Survey and the Current Population Survey, new evidence in support of procyclical search effort is presented. Average search effort of the unemployed is subject to cyclical composition biases.     

Trade and growth with heterogeneous firms

This paper explores the impact of trade on growth when firms are heterogeneous. We find that greater openness produces anti- and pro-growth effects. The Hopenhayn-Melitz-model selection effects raises the expected cost of introducing a new variety and this tends to slow the rate of new-variety introduction and hence growth. The pro-growth effect stems from the impact that freer trade has on the marginal cost of innovating. The balance of the two effects is ambiguous with the sign depending upon the exact nature of the innovation technology and its connection to international trade in goods and ideas. We consider five special cases (these include the Grossman-Helpman, the Coe-Helpman, and the Rivera-Batiz-Romer models) two of which suggest that trade harms growth; the others predicting the opposite.     

A selective review of the first 20 years of instrumental variables models in health-services research and medicine

Abstract

Background:

The method of instrumental variables (IV) is useful for estimating causal effects. Intuitively, it exploits exogenous variation in the treatment, sometimes called natural experiments or instruments. This study reviews the literature in health-services research and medical research that applies the method of instrumental variables, documents trends in its use, and offers examples of various types of instruments.     

变频器在水泥厂的应用实践

阐述我国新型干法熟料水泥生产线企业由粗放型、高能、高耗产业向节能、降耗的转变,而节能降耗主要表现为变频器的应用。以广西某单位使用的变频器为例,介绍了变频器的工作原理、使用变频器带来的节能效益以及高压变频器常见故障分析,西门子MM440低电压跳停故障的解决方法。     

Variable pricing business solutions in a decomposed business environment

Evolving business models and technology advances have facilitated the creation of innovative pricing strategies. Variable pricing represents the ability to configure a pricing schedule from a set of pricing options such as fixed cost, usage, shared benefit, and performance. The objective of variable pricing is to improve a pricing schedule for the mutual benefits of the provider and consumer, based on an evaluation of criteria that results in the setting of a price as a function of the expected value to be derived, as well as the time and materials used. In this paper, we focus on the variable pricing of ‘business solutions’, which is abstractly defined as the capabilities that enable or add value to the purposes of an enterprise. In a decomposed business environment, the structure of a business is partitioned into discrete business components that are assigned specific purposes and are endowed with resources to meet them. Business components interact to achieve business goals, and do so by exposing their capabilities through business services they offer. Business services have suitable levels of granularity offering constituent units of function, which, when selectively chosen and composed, form business solutions. We assert that business services are also suitable units for variable pricing, the implication being that pricing for a given business solution is an evaluation of the variable pricing of its assemblage of business services. The benefits of this ‘variable price composition’ approach offer greater accuracy for the pricing plan, coupled with increased flexibility to compose, modify, calculate and articulate pricing for business solutions.     

Pricing and hedging guaranteed minimum withdrawal benefits under a general Lévy framework using the COS method

This paper extends the Fourier-cosine (COS) method to the pricing and hedging of variable annuities embedded with guaranteed minimum withdrawal benefit (GMWB) riders. The COS method facilitates efficient computation of prices and hedge ratios of the GMWB riders when the underlying fund dynamics evolve under the influence of the general class of Lévy processes. Formulae are derived to value the contract at each withdrawal date using a backward recursive dynamic programming algorithm. Numerical comparisons are performed with results presented in Bacinello et al. [Scand. Actuar. J., 2014, 1–20], and Luo and Shevchenko [Int. J. Financ. Eng., 2014, 2, 1–24], to confirm the accuracy of the method. The efficiency of the proposed method is assessed by making comparisons with the approach presented in Bacinello et al. [op. cit.]. We find that the COS method presents highly accurate results with notably fast computational times. The valuation framework forms the basis for GMWB hedging. A local risk minimisation approach to hedging intra-withdrawal date risks is developed. A variety of risk measures are considered for minimisation in the general Lévy framework. While the second moment and variance have been considered in existing literature, we show that the Value-at-Risk (VaR) may also be of interest as a risk measure to minimise risk in variable annuities portfolios.     

应用于自适应格型RLS滤波器的变阶数算法

提出了一种新的变阶数(或抽头长度)算法,并将之应用于变阶数自适应格型递归最小二乘(RLS)滤波器的阶数更新中,讨论了格型滤波器阶数更新时相关参数的调整方法.新算法以分贝的形式比较短滤波器与长滤波器的时平均平方误差,采用自适应的抽头长度步长,能够在滤波器权值末收敛时同时快速更新滤波器长度与权值,且在不同大小噪声条件下都能收敛到最优阶数.理论分析与不同大小噪声条件下的自适应系统辨以仿真结果验证了新算法的有效性.     

价格传导关系变化的实证检验

利用变结构协整分析价格指数间从1996年10月～2010年7月的长期均衡关系,并对变结构前后价格传导路径的统计显著性做Granger因果检验结果显示,近年来上下游价格传导的统计显著性有较大提高,需求因素在价格传导中的作用突出,但是生产资料价格向下游传导存在较长的滞后期。最后利用变参数模型的状态空间表示,动态考察价格指数序列间的相互作用,发现各传导路径作用强度的变化并不一致。