Traditional portfolio optimization has been often criticized since it does not account for estimation risk. Theoretical considerations indicate that estimation risk is mainly driven by the parameter uncertainty regarding the expected asset returns rather than their variances and covariances....

Suppose that we are searching for the maximum of many unknown and analytically untractable quantities or, say, the 'best alternative' among several candidates. If our decision is based on historical or simulated data there is some sort of selection bias and it is not evident if our choice is...

In recent publications standard methods of random matrix theory were applied to principal components analysis of high-dimensional financial data. We discuss the fundamental results and potential shortcomings of random matrix theory in the light of the stylized facts of empirical finance....

The liberalization of electricity markets has triggered research in econometric modelling and forecasting of electricity spot prices. Moreover, both the demand and the supply of electricity are subject to weather conditions. Therefore, we examine the relation between hourly electricity spot...

As monopolies gave their way to competitive wholesale electricity markets, volumetric risk came into play. Electricity supplier can buy weather derivatives to protect from volumetric risk due to unexpected weather conditions. However, contracts can only be negotiated for weather variables...

Nonlinear autoregressive Markov regime-switching models are intuitive and frequently proposed time series approaches for the modelling of electricity spot prices. In this paper such models are compared to an ordinary linear autoregressive model with regard to their forecast performance. The...

Diese Studie untersucht Determinanten der Studiendauer und der Endnote von Kölner Studierenden im wirtschaftswissenschaftlichen Hauptstudium auf Grund einer Auswertung der Prüfungsdaten. Sie setzt eine entsprechende Studie über das Grundstudium (Mosler und Savine, 2004) fort. Die Ergebnisse...

Die Studie untersucht Determinanten der Studiendauer und der Endnote von Kölner Studierenden im wirtschaftswissenschaftlichen Grundstudium auf Grund einer Auswertung der Prüfungsdaten. Die Ergebnisse führen zu Empfehlungen für den individuellen Aufbau des Studiums und die Konzeption...

Area statistics are sample versions of areas occuring in a probability plot of two distribution functions F and G. This paper gives a unified basis for five statistics of this type. They can be used for various testing problems in the framework of the two sample problem for independent...

Standardmethoden zur Schätzung von Disparitätsmaßen aus klassierten Daten basieren entweder auf der Bestimmung von Schranken, die den wahren Wert des jeweiligen Disparitätsmaßes einschließen (nichtparametrischer Ansatz) oder aber auf Annahmen bezüglich der den Daten zugrunde liegenden...