NUSAP: a method to evaluate the quality of assumptions in quantitative microbial risk assessment

The Numeral Unit Spread Assessment Pedigree (NUSAP) system was implemented to evaluate assumptions in a quantitative microbial risk assessment (QMRA) model for Salmonella spp. in minced pork meat. This QMRA model allows the testing of mitigation strategies for the reduction of human salmonellosis and aims to serve as a basis for science‐based policy making. The NUSAP method was used to assess the subjective component of assumptions in the QMRA model by a set of four pedigree criteria: ‘the influence of situational limitations’, ‘plausibility’, ‘choice space’ and ‘the agreement among peers’. After identifying 13 key assumptions relevant for the QMRA model, a workshop was organized to assess the importance of these assumptions on the output of the QMRA. The quality of the assumptions was visualized using diagnostic and kite diagrams. The diagnostic diagram pinpointed assumptions with a high degree of subjectivity and a high ‘expected influence on the model results’ score. Examples of those assumptions that should be dealt with care are the assumptions regarding the concentration of Salmonella on the pig carcass at the beginning of the slaughter process and the assumptions related to the Salmonella prevalence in the slaughter process. The kite diagrams allowed a clear overview of the pedigree scores for each assumption as well as a representation of expert (dis)agreement. The evaluation of the assumptions using the NUSAP system enhanced the debate on the uncertainty and its communication in the results of a QMRA model. It highlighted the model’s strong and weak points and was helpful for redesigning critical modules. Since the evaluation of assumptions allows a more critical approach of the QMRA process, it is useful for policy makers as it aims to increase the transparency and acceptance of management decisions based on a QMRA model.     

Sharing Money Creation in a Monetary Union*

How to share money creation among the members of the European Monetary Union? To address this issue, we construct a two‐country New Open‐economy Macroeconomics model of an asymmetric monetary union with an incomplete financial market and home bias in consumption. We consider two sharing rules consistent with the current regulations of the European System of Central Banks. First, each participating National Central Bank supplies half of the European Central Bank determined money creation in the monetary union. Secondly, each National Central Bank adapts the national increase in money demand, under the constraint that the total money creation in the union does not exceed the level determined by the ECB for the whole union. We show that the current sharing rule, which ignores countries’ heterogeneity, is superior in terms of welfare. The key role of the current account is emphasized. It proves an efficient decentralized mechanism for allocation of money.     

Weighted norm inequalities and hedging in incomplete markets

Let be an -valued special semimartingale on a probability space with canonical decomposition . Denote by the space of all random variables , where is a predictable -integrable process such that the stochastic integral is in the space of semimartingales. We investigate under which conditions on the semimartingale the space is closed in , a question which arises naturally in the applications to financial mathematics. Our main results give necessary and/or sufficient conditions for the closedness of in . Most of these conditions deal with BMO-martingales and reverse H?lder inequalities which are equivalent to weighted norm inequalities. By means of these last inequalities, we also extend previous results on the F?llmer-Schweizer decomposition.     

Self-Insurance, Self-Protection and Market Insurance within the Dual Theory of Choice

As demonstrated by Ehrlich and Becker [1972], Expected Utility Theory predicts that market insurance and self-insurance are substitutes, whilst surprisingly, market insurance and self-protection could be complements. This article examines the robustness of this conclusion, as well as its extensions under the Dual Theory of Choice [Yaari, 1987]. In particular, the non-reliability of self-insurance activities, background risk and asymmetric information are considered.     

The optimal taxation of unskilled labor with job search and social assistance

In order to explore the optimal taxation of low-skilled labor, we extend the standard model of optimal nonlinear income taxation in the presence of quasi-linear preferences in leisure by allowing for involuntary unemployment, job search and an exogenous welfare benefit. In trading off low-skilled employment against work effort of higher skilled workers, the government balances distortions on the search margin with those on work effort. Higher welfare benefits typically reduce taxes paid by low-skilled workers and raise marginal tax rates throughout the skill distribution.     

Trading stamps: Their role in today's marketplace

This paper addresses the issue—Are trading stamps a viable means of retail competition in an inflationary economy? A brief history of trading stamps is presented, followed by a current examination of the industry. The paper concludes by discussing the results of a recent survey of 200 shoppers designed to answer the following questions: (1) consumers' ranking of the importance of trading stamps as a supermarket patronage motive; (2) determination if consumers believe trading stamps produce higher food prices; and (3) would consumers prefer a two percent cash discount in lieu of trading stamps.     

The current status of microcomputer usage in the marketing programs of AACSB-accredited colleges and universities

This paper presents the results of a comprehensive survey of microcomputer usage in marketing education today. This status report indicates that AACSB-accredited universities are making considerable progress in integrating microcomputers into their marketing programs.     

Testing for convergence of the Okun’s Law coefficient in Europe

Without convergence of macroeconomic parameters representative of the nature of adjustment mechanisms, even a common shock to members of a monetary union can lead to different macroeconomic consequences across the union and, eventually, to the need for more or less co-ordinated specific policies. In this paper, we test for the presence of convergence of the Okun’s Law coefficient (OLC) among several alternative groupings of European economies. The empirical strategy adopted is based on the evaluation of the time path of rolling regression estimates of the OLC for European countries. We then use a testing procedure suggested by Evans [Evans P (1996) J Econ Dynam Control 20:1027–1049] to investigate the convergence, or non-convergence, of the OLC in several groups of European countries by examining how the cross-country variance of the OLC evolves over time in these groups. A hypothesis of medium-term convergence of the OLC is rejected for most of the European country groups examined.      

Are there pecuniary compensations for working conditions?

In this paper we assess the relative contribution of working conditions to wage determination with an emphasis on differences along the earnings distribution. A survey of British employees in 2001 rich in questions regarding the job post enables us to separate the contribution of working conditions, job attributes and individual characteristics to the process of wage determination. Standard wage equations reveal that covariates such as having “repetitive job” and using generic skills such as “literacy” or “customer handling skills” are associated with significant premiums and penalties. Quantile regressions confirm the presence of penalties to poor working conditions, such as “working to tight deadlines”, that are significant in the middle section of the earnings distribution and robust to the inclusion of a wide range of controls for person, firm and other job characteristics. Counterfactual decompositions at quantiles show that, despite the apparent penalty, there are pecuniary compensations to poor working conditions around the first quartile and the median of the earnings distribution.     

Short Selling and the Weekend Effect in Nasdaq Stock Returns

We examine daily short selling of Nasdaq stocks to explore whether speculative short selling causes a significant portion of the weekend effect in returns. We identify a weekend effect in speculative short selling whereby it constitutes a larger percentage of trading volume on Mondays versus Fridays. We find an opposite effect in dealer short selling, consistent with market makers adding liquidity and stability. Our main finding is that speculative short selling does not explain an economically meaningful portion of the weekend effect in returns, even among the firms most that are most actively shorted. This finding contradicts some prior studies.