V. Wrischaftsordnung und soziale verfassung

Ohne Zusammenfassung     

Statistical Assessment of Numerical Models*

Evaluation of physically based computer models for air quality applications is crucial to assist in control strategy selection. The high risk of getting the wrong control strategy has costly economic and social consequences. The objective comparison of modeled concentrations with observed field data is one approach to assessment of model performance. For dry deposition fluxes and concentrations of air pollutants there is a very limited supply of evaluation data sets. We develop a formal method for evaluation of the performance of numerical models, which can be implemented even when the field measurements are very sparse. This approach is applied to a current U.S. Environmental Protection Agency air quality model. In other cases, exemplified by an ozone study from the California Central Valley, the observed field is relatively data rich, and more or less standard geostatistical tools can be used to compare model to data. Yet another situation is when the cost of model runs is prohibitive, and a statistical approach to approximating the model output is needed. We describe two ways of obtaining such approximations. A common technical issue in the assessment of environmental numerical models is the need for tools to estimate nonstationary spatial covariance structures. We describe in detail two such approaches.     

A TEST OF A GENERAL EQUILIBRIUM STOCK OPTION PRICING MODEL

An empirical version of the Cox, Ingersoll, and Ross (1985a) call option pricing model is derived, assuming execution price uncertainty in the options market. the pricing restrictions come in the form of moment conditions in the option pricing error. These can be estimated and tested using a version of the method of simulated moments (MSM). Simulation estimates, obtained by discretely approximating the risk-neutral processes of the underlying stock price and the interest rate, are substituted for analytically unknown call prices. the asymptotics and other aspects of the MSM estimator are discussed. the model is tested on transaction prices at 15-minute intervals. It substantially outperforms the Black-Scholes model. the empirical success of the Cox-Ingersoll-Ross model implies that the continuous-time interest rate implicit in synchronous transaction quotes of 90-day Treasury-bill futures contracts is an-albeit noisy-proxy for the instantaneous volatility on common stock. the process of the instantaneous volatility is found to be close to nonstationary. It is well approximated by a heteroskedastic unit-root process. With this approximation, the Cox-Ingersoll-Ross model only slightly overprices long-maturity options.     

A Consistent Poverty Approach to Assessing the Sensitivity of Income Poverty Measures and Trends

This paper examines the sensitivity of estimates of income poverty rates and trends to variations in the poverty line and to whether or not certain households are included or excluded from the sample used to estimate poverty. The approach draws on the concept of consistent poverty, which has been used to identify those with incomes below the poverty line who also experience deprivation. Our approach involves excluding households with incomes below the poverty line if they report zero or negative income or are self‐employed, have expenditure well in excess of their income, have substantial wealth holdings, or if they do not report having experienced financial stress over the past year. The combined impact of all four exclusions is to reduce the half‐median income poverty rate from 9.9 per cent to 5.4 per cent, but also suggests that poverty increased by more over the decade to 2003–04 than the original estimates indicate.     

How road improvement reduces poverty: the case of Laos

A general equilibrium modeling approach is used to study the effect that rural road improvement has on poverty incidence in Laos. Household survey data are used to distinguish three categories of rural villages according to their road access: (i) no vehicular access; (ii) dry season only access; and (iii) all weather access. A general equilibrium model of the Lao economy is then used to simulate, first, the effect of upgrading category (i) to category (ii) roads, and second, category (ii) to category (iii) roads. The former has a larger poverty‐reducing effect but is also more costly.     

Supplier strategy and customer responsiveness: Managing the links

Responsiveness to the customer is a fine ideal. Making it a reality is increasingly critical to gaining competitive advantage. In practice, it often means more variety at shorter notice. Faced with these challenges, companies must look to their suppliers for support. Instant market intelligence and flexible manufacturing are worth little if they face bottlenecks in getting the right supplies. Becoming customer responsive therefore starts with supplier strategy. Success requires better ways of managing the commercial links.     

Determination of the labour/capital multiplier of a typical modern irrigation scheme in South Africa∗

Methodology developed by the Central Economic Advisory Service was applied to gain greater insight into job creation benefits of a typical modern irrigation project. The evaluation method uses all relevant information available from economic feasibility analysis and relies on broad sectoral multipliers only where no better data are at hand. It is shown that contrary to current opinions based on broad sectoral aggregates, irrigation schemes do not necessarily exhibit above‐average job‐creasion advantages.     

Earnings management surrounding CEO changes

This paper investigates the extent of earnings management in the periods surrounding CEO changes by Australian firms. Evidence is presented of incoming CEOs undertaking earnings management to reduce income in the year of CEO change, with abnormal and extraordinary items being the primary vehicle through which this is achieved. This result is consistent with the notion of new CEOs engaging in an 'earnings bath', and is strongest for non–routine CEO changes, where the opportunities to manage earnings are greatest. Extending prior work, classification of CEO changes as routine or non–routine is based on an expanded information search, and this provides insights into the CEO change process and identifies problems with simpler mechanistic classification methods. Additionally, detailed information of the operation of the modified Jones model for estimating expected accruals is presented, and this is consistent with such models having low explanatory power in identifying abnormal accruals.     

The need for skills in the factory of the future

The 'automated factory' as the culmination of ingenuity has fascinated engineers and social visionaries (albeit for different reasons) for a considerable period. This article discusses the skill requirements of advanced automated production.