Piketty’s Elasticity of Substitution: A Critique

This article examines Thomas Piketty’s explanation of a falling wage share. Piketty explains rising income inequality between labor and capital as a result of one parameter of a production function: an elasticity of substitution, σ, between labor and capital greater than one. This article reviews Piketty’s elasticity argument, which relies on a non-standard definition of capital. In light of the theory of land rent, it discusses why the non-standard capital definition is a measure of wealth, not capital and is problematic for estimating elasticities. It then presents simple long-run estimates of σ in constant elasticity of substitution functions for Piketty’s data as well as for a subset of his capital measure that comes closer to the standard definition of productive capital. The estimation results cast doubt on Piketty’s hypothesis that σ is greater than one.     

Volatility and jump risk in option returns

We examine the importance of volatility and jump risk in the time-series prediction of S&P 500 index option returns. The empirical analysis provides a different result between call and put option returns. Both volatility and jump risk are important predictors of put option returns. In contrast, only volatility risk is consistently significant in the prediction of call option returns over the sample period. The empirical results support the theory that there is option risk premium associated with volatility and jump risk, and reflect the asymmetry property of S&P 500 index distribution.     

A new model of luggage storage time while boarding an airplane: An experimental test

The boarding process is on the critical path of the turn-around. Reduction in boarding time can benefit airline carriers and airports and improve passenger satisfaction. However, aisle interference caused by passengers placing their luggage during boarding is a key factor leading to cabin congestion and low boarding efficiency. Therefore, the storage time for the carry-on luggage and its influencing factors is analyzed in this study. An experiment was conducted in a B737-800 model (1/3 size) to explore the factors effecting the time of luggage storage, and a new effective model of luggage storage time is proposed through a significance test and data fitting. The results show that the age of passengers, the type and quantity of luggage, and the existing luggage in the luggage bin have a significant impact on the luggage storage time; the rule of the variation in luggage placing time is similar between young adult passengers and middle aged passengers; the impact of the existing luggage in the overhead bin on the luggage storage time shows a stable trend in the initial period, but with the quantity of the luggage increasing to a certain point, the luggage storage time begins to increase sharply, which is known as a “jump”; and the luggage type has a great influence on the threshold value of jump. The results of the study can provide a reference for airlines to manage cabin luggage to improve boarding efficiency and improve passenger experience.     

自密实混凝土配合比设计

针对实际工程要求和大连目前原材料现状,对原材料和工艺进行研究和采取优化措施,研究其对自密实混凝土性能尤其是匀质性的影响,进一步优化原材料、配合比和工艺,改善生产工艺,并应用于实际工程。     

外资进入的技术效率与资源配置效率研究——基于中国制造业微观数据的实证分析

本文引入一个与传统索洛余值方法相一致、同时具有微观基础的总生产率增长分析框架,采用1998~2007年中国制造业企业层面微观数据,实证考察了外资进入对制造业技术效率和资源配置效率的影响。结果表明,中国制造业整体总生产率的增长主要源于资源再配置效率,而外资的进入是资源配置效率提升的重要渠道之一。外资企业的总生产率增长高于制造业整体水平,其技术效率和资源配置效率也均高于制造业整体均值。样本考察期间,企业面临的市场环境有所改善,市场配置资源的效率不断提高。     

Technology adoption and the impact on average productivity

In this paper, a framework is developed to analyze how the specifications of new technologies and the heterogeneity of micro-units of production affect the input use, the adoption pattern, and the productivity of inputs. It shows that asset-productivity-enhancing (APE) technologies tend to be adopted by micro-units with high-quality assets, while variable-input, efficiency-enhancing (VIEE) technologies tend to be adopted by micro-units with low-quality assets. In both cases, the variable input productivity increases, but the average productivity of the fixed asset may decline in the case of the VIEE technology. The distribution of asset quality and the new technology specifications will therefore determine the impacts of production technology innovations on aggregate behavior and consequently the change in average productivity of the fixed asset.     

Asymmetric labour force participation decisions

This article finds compelling evidence of asymmetric labour force participation decisions across demographic groups in response to changes in labour market conditions. This behaviour is consistent with predictions from the standard labour-leisure choice model and suggests that asymmetry in individual behaviour plays some role in the observed asymmetry of the aggregate unemployment rate. It is estimated that the weighted average difference in response to a one percentage point change in unemployment rates is sizeable when compared to the average monthly change in the aggregate labour force.     

Who are the members of the international club?

This article proposes pragmatic methods that incorporate recent contributions to public good theory to identify the members of the international club and how they select new members. This article also suggests simple applications to the recent problems in international clubs such as the euro and NATO.     

Annuitization and aggregate mortality risk

It is well established that annuities can fully diversify idiosyncratic mortality risks. However, survival rates at the cohort level are changing, raising the question what is the scope of annuities in the presence of aggregate mortality risk? In an overlapping generations setting, we show that risk free annuities exist, but offer a return below the (fair) certainty equivalent return, and agents do not fully annuitize their savings. Higher aggregate mortality risk increases savings and thus the mean level of the capital stock. This lowers the mean rate of return on capital, the survival premium on annuities and the share of individual savings in annuities.     

The Time‐Varying Volatility of Earnings and Aggregate Consumption Growth

Time‐varying specifications for the conditional variance of earnings of U.S. households are estimated with micro data over the period 1968–92. The cross‐sectional mean of the estimated time‐varying uncertainty of individual households has a significant impact on aggregate consumption growth. As such, aggregate precautionary savings may be more important than what is suggested by the results of estimating standard regression equations for aggregate consumption growth that incorporate only lagged income growth and the real interest rate. The estimation of a buffer stock consumption model with time‐varying earnings uncertainty suggests that the precautionary savings motive is cyclical and has become less important in the 1980s.