Tax avoidance versus tax evasion: on some determinants of the shadow economy

In this paper we investigate how the possibility of (legal) tax avoidance affects the extent of (illegal) tax evasion and hence the shadow economy. We formulate a theoretical microeconomic model of household behavior in which households can participate in the official and in the shadow economy. Using comparative statics, we show that the complexity of the tax system affects participation in the shadow economy negatively, i.e. a more complex tax system with more possibilities of legal tax avoidance implies, ceteris paribus, a smaller labor supply in the shadow economy. In addition, we show that a reduction in the maximum admissible number of working hours in the official economy increases the labor supply in the shadow economy.     

Phase transition in the S&P stock market

We analyze the returns of stocks contained in the Standard & Poor’s 500 index from 1987 until 2011. We use covariance matrices of the firms’ returns determined in a time windows of several years. We find that the eigenvector belonging to the leading eigenvalue (the market) exhibits a phase transition. The market is in an ordered state from 1995 to 2005 and in a disordered state after 2005. We can relate this transition to an order parameter derived from the stocks’ beta and the trading volume. This order parameter can also be interpreted within an agent-based model.     

Confident expectations, rational expectations and the optimal conduct of monetary policy

Under what conditions central banks can afford to deviate from announced targets without losing their reputation is analyzed. For this, the public must have something like ‘confident expectations' vis-a-vis monetary policy and central banks have to behave accordingly. The paper shows that it can be rational for the public and welfare-increasing for the society to retain ‘confident expectations' instead of switching to rational expectations, when central banks have gained long-run reputation. At the end of the paper, alternative optimal money supply rules are compared in a dynamic optimization framework. © 1998 Elsevier Science B.V. All rights reserved.     

On economic applications of the genetic algorithm: a model of the cobweb type

This paper explores the idea of using artificial adaptive agents in economic theory. In particular, we use Genetic Algorithms (GAs) to model the learning behavior of a population of adaptive and boundedly rational agents interacting in an economic system. We analyze the behavior of a GA in two versions of a model of the cobweb-type, one in which firms make only quantity choices, and the other one in which firms first decide to exit or to stay in the market, and subsequently decide how much to produce. We present simulations with different coding schemes and interpret the rather surprising differences between the results for different setups by employing the mathematical theory for GAs with state-dependent fitness functions. In particular, we explain the relationship between coding and convergence properties of GAs.     

Hedge-Fonds als Asset-Klasse: Betrachtungen aus der Perspektive der deutschen Versicherungswirtschaft

The over performance of hedge funds until the current financial market turbulences led to a large number of insurers increasing their hedge funds quota. In the following this asset class is examined and particularly analyzed with respect to its adequacy for an insurance company's asset allocation by focusing on the axiom of safety, as demanded by national law. The problem of survivorship-bias and the Markowitz requirements of normal-distribution and constant correlations among the asset classes and their impact on a strategic asset allocation are studied.     

Rentenreform — mit welchem Fokus?

The demographic imbalance is aggravating, and by 2060 the old-age dependency ratio will double to approximately 70%. This development has consequences for the state pension system: growing contribution rates to social security coupled with lower pension levels, but at the same time a higher retirement age. The German pension scheme is mandatory for all wage and salary earners, but since 2001, no reasonable indicator for measuring the pension level exists any more. As a consequence of this, old-age pension has lost its traditional function as a replacement for earnings. The recent pension reforms have dropped the pension level sharply. Further reductions have been announced with the consequence of increasing old age poverty. Against this background it is proposed to raise the pension level so that the pensioners can maintain their standard of living. But any pension reform involves issues of distribution between and often also within generations, which cannot be addressed without explicit equity criteria. Some authors consider the past reforms as a mistake, others suggest adjustments.     

Der US-Dollar als Leitwährung – alternativlos?

The importance of the industrialized countries – including the USA – for world production has been declining for a long time. By contrast, China’s share in particular has increased significantly. Nevertheless, the US dollar has largely fulfilled the criteria for a leading currency function so far, even if this is increasingly criticised due to the protectionist rhetoric of the US. Accordingly, central banks worldwide hold their reserves primarily in US dollars and transactions are largely conducted in US currency. This position brings great advantages–such as making it easier for the US to monitor and enforce sanctions, among other things–and therefore great incentives for the US to maintain its position as the leading currency. Whether other currencies, especially the renminbi, will be able to fulfil the lead currency function is questionable. Similarly, it does not seem realistic that market participants will be able to engage in a global currency.     

R&D competition versus R&D cooperation in oligopolistic markets with evolving structure

This paper considers investment behavior of duopolistic firms subject to technological progress. It is assumed that initially both firms offer a homogeneous product, but after a stochastic waiting time they are able to implement a product innovation. Production capacities of both firms are product specific. It is shown that firms anticipate a future product innovation by under-investing (if the new product is a substitute to the established product) and higher profits, and over-investing (in case of complements) and lower profits, compared to the corresponding standard capital accumulation game. This anticipation effect is stronger in the case of R&D cooperation. Furthermore, since due to R&D cooperation firms introduce the new product at the same time, this leads to intensified competition and lower firm profits right after the new product has been introduced. In addition, we show that under R&D competition the firm that innovates first, overshoots in new-product capacity buildup in order to exploit its temporary monopoly position. Taking into account all these effects, the result is that, if the new product is neither a close substitute nor a strong complement of the established product, positive synergy effects in R&D cooperation are necessary to make it more profitable for firms than R&D competition.