Optimal design for discrete choice experiments

In this paper we derive locally optimal designs for discrete choice experiments. As in Kanninen (2002) we consider a multinomial logistic model, which contains various qualitative attributes as well as a quantitative one, which may range over a sufficiently large interval. The derived optimal designs improve upon those given in the literature, but have the feature that every choice set contains alternatives, which coincide in all but the quantitative attributes. The multinomial logistic model will then lead to a response behavior, which is apparently unrealistic.     

The impact of period effects on dose level contrasts in alternating cross‐over designs for first‐time‐in‐human studies

For first‐time‐in‐human studies with small molecules alternating cross‐over designs are often employed and at study end are analyzed using linear models. We discuss the impact of including a period effect in the model on the precision with which dose level contrasts can be estimated and quantify the bias of least squares estimators if a period effect is inherent in the data that is not accounted for in the model. We also propose two alternative designs that allow a more precise estimation of dose level contrasts compared with the standard design when period effects are included in the model. Copyright © 2010 John Wiley & Sons, Ltd.     

Aging and inactivity—capitalizing on the protective effect of planned physical activity in old age

The paper discusses two parallel biocultural trends—aging and inactivity. The principle of economy in movement in modern society versus the dependency of human beings on movement for their development and health is described. The results of inactivity are sometimes mistakenly considered irreversible losses caused by aging, but in actual fact, inactivity accelerates the irreversible losses caused by the aging process. The paper then describes the contribution of physical activity in terms of increasing positive aspects or decreasing risks: increasing life expectancy or decreasing risk of mortality, increasing cardiovascular fitness or decreasing risk of cardiovascular disease, increasing muscle mass or decreasing falls and instability, improving cognitive performance or reducing cognitive decline and neurological disorders, and improving well-being or reducing depression. The optimal dose of physical activity is then described, followed by recommendations for further research on mechanisms determining physical activity behavior.     

Some statistical properties of Hadamard products of random matrices

The mean of the Hadamard product of two linear combinations of a random matrix is presented in terms of the mean and variance of the random matrix for any distribution. The variance is given for the normal distribution. Further, the means of four Hadamard products of matrix bilinear forms in a normally distributed random matrix are given. Finally, the mean of a quadruple Hadamard product of linear combinations is derived under normality. Received: January 5, 2000; revised version: April 3, 2000     

The role of mitochondria in conserved mechanisms of aging

The European research project MiMage, supported by the European Community's Sixth Framework for Research and Technological Development, focuses on elucidating the role of mitochondria in conserved mechanisms of aging. This Perspective summarizes a selection of talks presented in April 2006 at the second MiMage symposium by members from participating laboratories and invited speakers.     

The net asset value and stock prices of European real estate companies

The frequently large divergences between share price and net asset value (NAV) of listed real estate companies have been a key topic in real estate research for many years. However, previous research has mainly focused on the U.S. market, concentrating on companies’ performance ratios related to information from balance sheet statements and/or income statements as well as information from the stock market, and its results are not satisfying. This study, on the other hand, focuses on the European real estate market and presents a semi-rational model for explaining NAV spreads, taking into account performance ratios and market sentiment simultaneously. It appears that market sentiment in particular substantially improves the model, which explains more than 76% of the NAV spread. Thus, the developed model constitutes a significant improvement over previous studies on the explanation of NAV spreads.