劣势耐用品厂商的产品质保期与质保服务投入策略研究

在实际中，消费者购买耐用品时均同时获得厂商提供的质保服务，由于产品质保服务影响着消费者的产品使用效用，因此耐用品定价、质保期和产品质保服务投入是影响厂商利润的主要因素。考虑双寡头市场环境下，建立微分博弈模型讨论单位产品质保服务投入和产品质保期对双寡头厂商均衡价格的影响。结论表明双寡头厂商的单位产品质保服务投入越高、质保期越长，均衡价格越高；但单位产品保服务投入与质保服务对消费者效用影响系数的关系影响着竞争对手在均衡价格的变化趋势；劣势的低质量厂商可以通过增加单位产品质保服务投入策略或延长质保期的策略实现在均衡下与高质量厂商以同等价格销售耐用品，但劣势厂商增加单位产品质保服务投入策略要优于延长质保期策略。最后，利用数值分析进一步验证了所得结论的有效性。     

New innovational outlier unit root test with a break at an unknown time

The Perron test which is based on a Dickey–Fuller test regression is a commonly employed approach to test for a unit root in the presence of a structural break of unknown timing. In the case of an innovational outlier (IO), the Perron test tends to exhibit spurious rejections in finite samples when the break occurs under the null hypothesis. In the present paper, a new Perron-type IO unit root test is developed. It is shown in Monte Carlo experiments that the new test does not over-reject the null hypothesis. Even for the case of a level and slope break for trending data, the empirical size is near its nominal level. The test distribution equals the case of a known break date. Furthermore, the test is able to identify the true break date very accurately even for small breaks. As an application serves the Nelson–Plosser data set.     

Size distortion of asymmetric unit root tests in the presence of level shifts

The finite-sample size properties of momentum-threshold autoregressive (MTAR) asymmetric unit root tests are examined in the presence of level shifts under the null hypothesis. The original MTAR test using a fixed threshold is found to exhibit severe size distortion when a break in level occurs early in the sample period, leading to an increased probability of an incorrect inference of asymmetric stationarity. For later breaks the test is also shown to suffer from undersizing. In contrast, the use of consistent-threshold estimation results in a test which is relatively robust to level shifts.     

Personal networks typologies: A structural approach

Building typologies allows to compare networks on multiple dimensions, and to approach a generalization grounded on empirical data. In this article, we present a typology of personal networks only based on indicators related to the structure of relations between alters. It is designed from very detailed data on young French people who were involved in a longitudinal study. Our typology mobilizes a small number of indicators to discriminate the types that compose it. In so doing, we intend to make it applicable to various surveys.     

Did small and medium enterprises maintain better jobs during the early years of the recession? Job quality multidimensional evidence from Spain

While the literature has indeed confirmed a general tendency linking small and medium enterprises (SMEs) to a dynamic of greater job creation, there is little available evidence on what has happened to job quality since the financial crisis. Through a representative sample of 5311 employees in 2008 (first year of job destruction) and 4925 employees in 2010 (last year for which data were available), and using a two-stage structural equation model, this article empirically analyses the multidimensional determinants of job quality, by enterprise-size class, in Spain. The research has revealed three main results. First, job quality in Spain improved in all enterprises, regardless of their size, during the early years of the recession. Second, the greatest improvements were found in SMEs. Although job quality was already better in SMEs than in large enterprises in 2008, the differences between them subsequently widened. Third, this accelerated divergence was explained by the following dimensions: working conditions, work intensity, health and safety at work, and work–life balance. These dimensions were much more positive in SMEs. Employment-related public policy should therefore focus more specifically on SMEs. There are two reasons for this. First, despite the recession, SMEs have shown themselves to be key factors in the explanation of job quality. Second, by making changes to their value generation model, they could continue to drive the creation of better quality jobs.     

The Food Crisis and its Impacts on Poverty in Senegal and Mali: Crossed Destinies

This article uses two CGE macro‐micro models to analyse the distributional impact of the food crisis and policy responses in two neighbouring African countries, both of which are strongly dependent on agriculture. The approach captures structural differences at both the macro and micro level for household income and expenditure structures, and the results reveal differences for poverty impact at the national and sub‐group levels, as well as for inequality and pro‐poor analysis. The importance of country‐specific analysis and the risk of extrapolating conclusions from one country to another are also highlighted.     

Comment on “Constrained Optimization Approaches to Estimation of Structural Models”

We revisit the comparison of mathematical programming with equilibrium constraints (MPEC) and nested fixed point (NFXP) algorithms for estimating structural dynamic models by Su and Judd (2012). Their implementation of the nested fixed point algorithm used successive approximations to solve the inner fixed point problem (NFXP‐SA). We redo their comparison using the more efficient version of NFXP proposed by Rust (1987), which combines successive approximations and Newton–Kantorovich iterations to solve the fixed point problem (NFXP‐NK). We show that MPEC and NFXP are similar in speed and numerical performance when the more efficient NFXP‐NK variant is used.     

A Dynamic Reinterpretation of Nash Bargaining With Endogenous Threats

This paper concerns the two‐stage game introduced in Nash (1953). It formalizes a suggestion made (but not pursued) by Nash regarding equilibrium selection in that game, and hence offers an arguably more solid foundation for the “Nash bargaining with endogenous threats” solution. Analogous reasoning is then applied to an infinite horizon game to provide equilibrium selection in two‐person repeated games with contracts. In this setting, issues about enforcement of threats are much less problematic than in Nash's static setting. The analysis can be extended to stochastic games with contracts.     

Issues in Estimating New Keynesian Phillips Curves in the Presence of Unknown Structural Change

Many articles which have estimated models with forward looking expectations have reported that the magnitude of the coefficients of the expectations term is very large when compared with the effects coming from past dynamics. This has sometimes been regarded as implausible and led to the feeling that the expectations coefficient is biased upwards. A relatively general argument that has been advanced is that the bias could be due to structural changes in the means of the variables entering the structural equation. An alternative explanation is that the bias comes from weak instruments. In this article, we investigate the issue of upward bias in the estimated coefficients of the expectations variable based on a model where we can see what causes the breaks and how to control for them. We conclude that weak instruments are the most likely cause of any bias and note that structural change can affect the quality of instruments. We also look at some empirical work in Castle et al. (2014 Castle, J. L., Doornik, J. A., Hendry, D. F., Nymoen, R. (2014). Misspecification testing: non-invariance of expectations models of inflation. Econometric Reviews 33:5–6, 553–574, doi:10.1080/07474938.2013.825137[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) on the new Kaynesian Phillips curve (NYPC) in the Euro Area and U.S. assessing whether the smaller coefficient on expectations that Castle et al. (2014 Castle, J. L., Doornik, J. A., Hendry, D. F., Nymoen, R. (2014). Misspecification testing: non-invariance of expectations models of inflation. Econometric Reviews 33:5–6, 553–574, doi:10.1080/07474938.2013.825137[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]) highlight is due to structural change. Our conclusion is that it is not. Instead it comes from their addition of variables to the NKPC. After allowing for the fact that there are weak instruments in the estimated re-specified model, it would seem that the forward coefficient estimate is actually quite high rather than low.     

农村经济、社会福利与区域非均衡性研究

我国农村经济增长与社会福利存在明显的区域非均衡性,二者均呈现出自东部向西部递减的规律;大部分省、市经济增长和社会福利的耦合度经历了从勉强协调向基本协调过渡的发展过程,二者的协调程度还有进一步提升的空间;经济增长指数与耦合度表现出了一致的波动性,经济子系统对整个系统具有牵引作用.当前,加快发展农村经济,扩大对农村地区的必要性供给,推进农村地区的城镇化进程是实现我国农村地区经济增长与社会福利协同发展的有效途径.