Regional Impact of the German Rent Brake

New rental contracts have risen dramatically in many German places in recent years due to strong influxes and sluggish construction activity. The rent brake should put a stop to this development so that housing in prospering cities remains affordable for people on normal and low incomes. Although initial successes were attested to the rent brake, empirical findings are increasing, according to which the rent brake is not having the desired effect. This also applies to the findings determined here: the results of a difference‐in‐difference estimation show that the rent brake has reduced rents on offer in Hamburg, Berlin and Munich by up to 5%, while no effects are observed in Cologne and Düsseldorf. Nevertheless, the effects are lagging behind the expected effects almost everywhere. The results illustrate once again an implementation deficit and show that no general statements on the effectiveness of the rent brake are currently permissible. However, the rent brake is certainly having a price effect in some regions, even if not to the intended extent.     

Every flow has its ebb: The impact of flow on work–family conflict and adjustment in global careers

Despite an increase in research in psychology on the mental state of flow, little is known within the area of organisational studies about its “dark side.” Although prior organisational studies literature suggests that flow leads to generally positive work outcomes, we use conservation of resources theory to argue that expatriates in the state of flow can accumulate resources that lead to work adjustment but at the same time may experience unintended negative work–family conflict consequences. Specifically, we argue that being in the state of flow can improve expatriates' work adjustment because they can concentrate on the task at hand in an unencumbered way. Yet the exclusive concentration on work tasks and the distortion of time while in the state of flow may reduce psychological and time resources available to the family, resulting in work–family conflict. We explore whether flow theory needs to be altered to discover potentially negative work–family conflict outcomes inherent in the complex work regimes associated with global careers. Structural equation modelling analyses based on a sample of 230 expatriates in the United States and 169 expatriates in Brazil revealed that flow increased both work–family conflict and work adjustment.     

The adoption and diffusion of high-performance management: lessons from Japanese multinationals in the West

This paper draws on surveys and case studies of management practicesin Japanese transplants in the US, the UK and France to studypossible impediments to introducing high-performance work practices.It shows significant national differences in the adoption ofspecific practices and in their clustering. While the exerciseof power by labour and management and public policy result innationally specific hybrid arrangements, the results demonstratea common pattern in types of traditional practices that surviveand of Japanese practices transferred. The most commonly adoptedpractices (such as teamwork and quality circles) relate directlyto management interests in productive efficiency, while theretained traditional practices most often relate to worker compensationand internal labour market structures. National industrial relationssystems appear to be important in the balancing of efficiencygains for managers and economic benefits for workers.     

Dose–response modelling for bivariate covariates with and without a spike at zero: theory and application to binary outcomes

In epidemiology and clinical research, there is often a proportion of unexposed individuals resulting in zero values of exposure, meaning that some individuals are not exposed and those exposed have some continuous distribution. Examples are smoking or alcohol consumption. We will call these variables with a spike at zero (SAZ). In this paper, we performed a systematic investigation on how to model covariates with a SAZ and derived theoretical odds ratio functions for selected bivariate distributions. We consider the bivariate normal and bivariate log normal distribution with a SAZ. Both confounding and effect modification can be elegantly described by formalizing the covariance matrix given the binary outcome variable Y. To model the effect of these variables, we use a procedure based on fractional polynomials first introduced by Royston and Altman (1994, Applied Statistics 43: 429–467) and modified for the SAZ situation (Royston and Sauerbrei, 2008, Multivariable model‐building: a pragmatic approach to regression analysis based on fractional polynomials for modelling continuous variables, Wiley; Becher et al., 2012, Biometrical Journal 54: 686–700). We aim to contribute to theory, practical procedures and application in epidemiology and clinical research to derive multivariable models for variables with a SAZ. As an example, we use data from a case–control study on lung cancer.     

Transaction Costs,Option Prices,and Model Risk in Fair Value Accounting

This paper examines the reliability of option fair value estimates in the presence of transaction costs. The Black Scholes Merton (BSM) framework assumes zero transaction costs and thus might not provide a reasonable approximation in this context. We investigate the model adjustments companies make to their BSM models to deal with these transaction costs. We specifically examine Employee Stock Option (ESO) plans listed on the French stock exchange, as detailed disclosure on modeling is available for these ESOs. Our analysis questions the reliability of these model adjustments, especially their bias and the extent to which they provide a faithful representation of option fair values. Holding parameter values constant, we find that the model adjustments lead to a median understatement of 52% compared to the BSM model price, higher than the discount we observe for the opportunistic determination of model parameters (below 20%). The paper contributes to the fair value literature by highlighting model risk in the fair valuation of options. This model risk stems from assumptions made about the size of transaction costs and complements the notion of parameter risk analyzed in previous literature. As a result, the model itself might be a possible channel for fair value management.     

Using column generation to solve extensions to the Markowitz model

Abstract

We introduce a solution scheme for portfolio optimization problems with cardinality constraints. Typical portfolio optimization problems are extensions of the classical Markowitz mean–variance portfolio optimization model. We solve such types of problems using a method similar to column generation. In this scheme, the original problem is restricted to a subset of the assets resulting in a master convex quadratic problem. Then the dual information of the master problem is used in a subproblem to propose more assets to consider. We also consider other extensions to the Markowitz model to diversify the portfolio selection within given intervals for active weights.     

Pre-Kommunikation im Internet — Der BMW X1 trifft Kunden im Social Web

Kunden suchen heute verst?rkt im Social Web nach der Unterstützung anderer Kunden bei der Kaufentscheidung und entscheiden selbst, welche Inhalte sie über welche Kan?le abrufen. Unternehmen sollten daher das Social Web für die Pre-Kommunikation nutzen. Das Praxisbeispiel der BMW Group zeigt, wie man damit die Bekanntheit steigern und neue Zielgruppen erreichen kann.