The Genesis of the Golden Age - Accounting for the Rise in Health and Leisure

We develop a life cycle model featuring an optimal retirement decision in the presence of physiological aging. In modeling the aging process we draw on recent advances within the fields of biology and medicine. In the model individuals decide on optimal consumption during life, the age of retirement, and (via health investments) the timing of their death. Accordingly, "years in retirement" is fully endogenously determined. Using the model we can account for the evolution of age of retirement and longevity across cohorts born between 1850 and 1940 in the US. Our analysis indicates that 2/3 of the observed increase in longevity can be accounted for by wage growth, whereas the driver behind the observed rising age of retirement appears to have been technological change in health care. Both technology and income contribute to the rise in years in retirement, but the contribution from income is slightly greater.Aging, Longevity, Retirement, Health, Health Technolog

Fractionalization

We provide new measures of ethnic, linguistic, and religious fractionalization for about 190 countries. These measures are more comprehensive than those previously used in the economics literature and we compare our new variables with those previously used. We also revisit the question of the effects of ethnic, linguistic, and religious heterogeneity on the quality of institutions and growth. We partly confirm and partly modify previous results. The patterns of cross-correlations between potential explanatory variables and their different degree of endogeneity makes it hard to make unqualified statements about competing explanations for economic growth and the quality of government. Our new data, which features the underlying group structure of ethnicities, religions and languages, also allows the computation of alternative measures of heterogeneity, and we turn to measures of polarization as an alternative to the commonly used index of fractionalization. © 2003 Kluwer Academic Publishers

Safe Assets’ Scarcity, Liquidity and Spreads

This paper constructs a simple general equilibrium model to analyse the interactions between the financial and the real sector in an environment where liquidity holdings is an input of the credit/investment process. The supply of liquidity is constrained in that income pledgeability limits inside liquidity, and not all sovereign debt is safe/liquid. We pin down the determinants of liquidity/collateral premia and bond spreads, and with reference to the eurozone: (i) the implications of the ECB’s policies on liquidity provision and credit, and (ii) the debt management policy that would increase welfare with no need for transfer payments

The Division of Labor in Teams: A Conceptual Framework and Application to Collaborations in Science

Even though teams have become the dominant mode of knowledge production, little is known regarding how they divide work among their members. Conceptualizing knowledge production as a process involving a number of functional activities, we first develop a conceptual framework to study the division of labor in teams. This framework highlights three complementary perspectives: (1) individual level (the degree to which team members specialize vs. work as generalists), (2) activity level (the degree to which activities are concentrated among few team members vs. distributed among many) and (3) the intersection between the two (e.g., which activities are performed jointly by the same individual). We then employ this framework to explore team-based knowledge production using a newly available type of data – the disclosures of author contributions on scientific papers. Using data from over 12,000 articles, we provide unique descriptive insights into patterns of division of labor, demonstrating the value of the three complementary perspectives. We also apply the framework to uncover differences in the division of labor in teams of different size, working in novel vs. established fields, and on single vs. interdisciplinary projects. Finally, we show how division of labor is related to the quality of teams’ research output. We discuss opportunities for extending and applying our framework as well as implications for scientists and policy makers

The Statistical Performance of Econometric and Implied Forecasting Models

This study examines the statistical performance of various econometric and implied correlation models applied to over-the-counter currency options. In evaluating the predictive accuracy of the forecast models, statistical performance measures, mainly in the form of the root mean squared forecast errors (RMSFE), are employed. Interestingly, we find that a simple exponential weighting scheme for variances produce the best results. Such models are very simple to estimate and forecast, thus potentially rendering considerably more complex and cumbersome models, such as the multivariate generalized autoregressive conditional heteroscedasticity (GARCH), hardly worth the additional effort

A Transformerless Medium Voltage Multiphase Motor Drive System

A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV) multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP), a complete improved Phase Disposition Pulse Width Modulation (PD-PWM) method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.cascaded H-bridge converter; motor drive; multiphase motor; PD-PWM; transformerles

An Approach to Scientific Economics

An interdisciplinary approach is proposed to improve scientific reliability. Economics encompasses all fields, and is governed by both natural law and human law. Universally valid relationships can be derived from the human law (e.g. on banking) to complement those of natural science. The approach is illustrated by experiments that demonstrate reliable logical relationships in human behaviour and important characteristics defining money. Science cannot predict the future, but universally valid relationships apply reliably to hypothetical circumstances. “Though we may be uncertain as to the storms that may blow, we can design to best withstand those storms we elect to defineâ€

The Change of Job Opportunities: the Role of Computerization and Institutions

This paper studies the pattern of job opportunities over the last two decades in European countries. We find that the share of high-skilled jobs have been expanding over time, while the share of medium- skilled jobs have been declining. These changes are in line with the US patterns and, according to the previous literature, they come from recent technological changes. However, our data show an interesting difference between the US and Europe: in Europe there is not any increase in the share of low-skilled employment. Moreover, we find that the difference between the proportion of employment hired in low-skilled and medium-skilled jobs is negatively correlated with both the unemployment rate and the degree of employment protection in the labour market. We propose a theoretical model to study the effects of a technological shock on the employment structure in a unionized economy. By accounting for the collective bargaining process, our model may fit Continental Europe better than the previous ones. We conclude that the definition of the union policy is crucial in order to explain observed cross-country heterogeneity in low-skilled employment

Would you like to enter first with a low-quality good?

Using a two-period duopoly model with vertical differentiation, we show that there exists a unique subgame perfect equilibrium where the first entrant supplies a lower quality and gains higher profits than the second entrant. We also prove that this entry sequence is also socially efficient