Are mobile and fixed broadband substitutes or complements? New empirical evidence from Italy and implications for the digital divide policies

The literature on broadband policies has been focusing on the possible role of mobile broadband as a means for addressing geographical digital divide in areas with no or inadequate fixed broadband infrastructure coverage. Broadband plans designed by most of the industrialized countries take the substitutability between fixed and mobile technologies for granted, with restrictions essentially relating only to bandwidth performance. We explore the determinants of individuals' private access (away from work) to the Internet with the smartphone through a mobile broadband connection, focusing on the role played by Internet uses and taking into account the availability of a fixed broadband connection at home. The results of our econometric exercise, carried out on microdata referred to Italian individuals, provide original and interesting evidence: a complementarity effect between mobile and fixed broadband is found for browsing, video streaming, gaming and cloud services; a substitution effect emerges for social networking and music streaming. Such increasing complexity of individuals’ broadband usage patterns should be acknowledged in the way broadband coverage is mapped and policies designed, adopting a more ecosystem-oriented approach which integrates supply- and demand-side features. A first step in this direction is the inclusion of some, so far neglected, key-attributes of the demand (data traffic allowance, latency, ease of interconnection with Internet capable devices) among the relevant dimensions of policy design.     

Understanding the retirement-consumption puzzle through the lens of food consumption-fuzzy regression-discontinuity evidence from urban China

This paper provides an understanding of the widely-documented retirement-consumption puzzle from the perspective of food consumption. Exploiting the mandatory retirement age cut-off for public-sector male employees in urban China to obtain a source of exogenous variation in their retirement status, this paper identifies the causal impacts of retirement on four major aspects of their food consumption: food expenditure, time spent in food acquisition, the quantity and quality of food consumed. Based on data from the China Health and Nutrition Survey, our fuzzy regression-discontinuity analysis finds that, consistent with the retirement-consumption puzzle, retirement reduces elderly males’ total food expenditure by 49–55%. However, retirement barely changes the quantity of food they consume (measured by total calorie intakes). Further analysis suggests that elderly males substitute time for money in food acquisition upon retirement, which helps to reconcile the differential impacts of retirement on food expenditure and food consumption. Finally, retirement greatly changes elderly males’ diet structure. They consume significantly less food with animal origins (and thus less fat and protein) and more grains (and thus more carbohydrate) upon retirement, which undermines their diet balance by the standards provided by the Chinese Nutrition Association.     

On Professor Takashi Negishi's contributions to economic theory

Professor Takashi Negishi has made fundamental contributions to economic theory on an extremely broad range of topics. As the editors of this special issue, we feel extremely fortunate that each of us has worked on topics with respect to which Professor Negishi's influences have been particularly large. In this introductory article, each of us will discuss Professor Negishi's influence on the topic we are most familiar with. For the entire spectrum of his research, readers are referred to the list of Professor Negishi's publications presented at the end of this article.     

Macroeconomic effects of an indirect tax substitution

We study an indirect tax reform in a general equilibrium model with imperfect competition for both the Cournot and the Free entry equilibria. We show that it is possible to attain a positive balanced budget multiplier by means of a substitution of specific by ad valorem taxation. Moreover, although any tax substitution causes higher prices and the flow up of firms in the long-run, the Free entry equilibrium output can increase with respect to that of the Cournot equilibrium. Finally, in contrast with the partial equilibrium, welfare decreasing tax reforms are likely to occur even when the balanced budget multiplier is positive.      

Factor substitution and factor intensities in models with more factors than goods

This paper considers the commodity prices–factor prices relation in models with more factors than consumption goods. Under some simple factor substitutability assumptions, many results in the   n  ×  n   cases have counterparts in the   l  ×  n   cases. The proportional price changes of the "middle factors" will be trapped between those of the "extreme factors". A weak and a strong Stolper–Samuelson theorem can also be proven. If the numbers of goods and perfectly complementary factors are equal and the production functions have the nested constant elasticity of substitution form, two of the complementary factors would have the most extreme relative price changes, regardless of the factor intensities.     

Intertemporally dependent preferences and optimal dynamic behavior

We study a model of optimal dynamic behavior in which the intertemoral preferences preserve the time additively separable framework of Ramsey models, while exhibiting Edgeworth–Pareto complementarity between consumption in adjacent periods. We identify economic environments in which global optimal dynamics under intertemporal complementarity exhibits persistent fluctuations even though the misspecified Ramsey-type theory, under the intertemporal independence assumption, predicts monotone convergence.     

CLOSED-FORM SOLUTIONS FOR OPTIMAL PORTFOLIO SELECTION WITH STOCHASTIC INTEREST RATE AND INVESTMENT CONSTRAINTS

We examine the portfolio choice problem of an investor with constant relative risk aversion in a financial market with partially hedgeable interest rate risk. The individual shadow price of the portfolio constraint is characterized as the solution of a new backward equation involving Malliavin derivatives. A generalization of this equation is studied and solved in explicit form. This result, applied to our financial model, yields closed-form solutions for the shadow price and the optimal portfolio. The effects of parameters such as risk aversion, interest rate volatility, investment horizon, and tightness of the constraint are examined. Applications of our method to a monetary economy with inflation risk and to an international setting with currency risk are also provided.     

网上零售影响社会物流发展的定量分析

通过多元线性回归等方法分析,在其他因素不变情况下,发现网上零售交易规模的边际社会物流需求大于零并且呈现递减规律,网上零售市场发展可促进高效率物流对低效率物流的替代作用。     

Fungicide resistance and misinformation: A game theoretic approach

Fungicide resistance is a serious problem for agriculture today. This analysis provides additional insight into the strategic behavior of farmers when their fungicide use generates a negative intertemporal production externality in the form of fungicide resistance. We find that when farmers encounter this type of externality, they choose fungicide levels that exacerbate fungicide resistance. We examine a compensation mechanism in which a farmer reduces fungicide use in exchange for a transfer. This mechanism reduces fungicide use; however, misinformation about the severity of fungicide resistance generates distortions. We find that one-sided misinformation could lead a farmer to choose socially optimal fungicide levels, which makes the compensation mechanism less necessary. In addition, we show that when both farmers are misinformed, the mechanism could lead farmers to choose fungicide levels below the socially optimal level depending on their pessimistic beliefs about the severity of fungicide resistance.     

木材节约代用理论述评

在讨论了木材节约代用基本涵义的基础上,总结了中国木材节约代用的历史发展,提出了当前中国发展木材节约代用的背景,介绍了国内外木材节约代用理论,并根据作者对木材节约代用的认识,对国内外木材节约代用理论进行了比较和评价。