Time Horizon and Cooperation in Continuous Time

We study social dilemmas in (quasi‐) continuous‐time experiments, comparing games with different durations and termination rules. We discover a stark qualitative contrast in behavior in continuous time as compared to previously studied behavior in discrete‐time games: cooperation is easier to achieve and sustain with deterministic horizons than with stochastic ones, and end‐game effects emerge, but subjects postpone them with experience. Analysis of individual strategies provides a basis for a simple reinforcement learning model that proves to be consistent with this evidence. An additional treatment lends further support to this explanation.     

A test for the global minimum variance portfolio for small sample and singular covariance

AStA Advances in Statistical Analysis - Recently, a test dealing with the linear hypothesis for the global minimum variance portfolio weights was obtained under the assumption of non-singular...     

The Role of Information in Repeated Games With Frequent Actions

We show that in repeated interactions the avenues for effective provision of incentives depend crucially on the type of information players observe. We establish this conclusion for general repeated two‐player games in which information arrives via a continuous‐time stationary process that has a continuous multidimensional Brownian component and a Poisson component, and in which the players act frequently. The Poisson jumps can be used to effectively provide incentives both with transfers and value burning, while continuous Brownian information can be used to provide incentives only with transfers.     

The Impact of the Economic Transition in Poland on Vulnerable Populations

The economic changes that began with the fall of communism in 1989 have helped Poland to establish one of the strongest economies in Eastern Europe today. Not all parts of society have benefited equally from the positive economic picture however. Those who are unemployed, living on a pension, single parents, or residents of rural communities are at risk of living in poverty in Polands new economic environment. This paper assesses the views of people in these four groups in terms of their perceived need for basic necessities (money for food, rent, and medicine) and for luxury activities (culture, relaxation, and education). The findings have implications for social welfare policies and services in Poland.The authors wish to thank Kazimierz M. Slomczynski for use of the POLPAN data.     

More-for-less algorithm for fixed-charge transportation problems

The more-for-less (MFL) phenomenon in distribution problems occurs when it is possible to ship more total goods for less (or equal) total cost, while shipping the same quantity or more from each origin and to each destination. This paradox occurs often in fixed-charge transportation problems (FCTPs), and further analysis could bring significant reduction in costs. The MFL phenomenon for FCTPs has received minimal attention in the literature despite the fact that existing analytical algorithms, such as branch and bound, are limited to small problems due to excessive computational effort. In this paper, we develop a simple heuristic algorithm to identify the demand destinations and the supply points to ship MFL in FCTPs. The proposed method builds upon any existing basic feasible solution. It is easy to implement and can serve as an effective tool for managers for solving the more-for-less paradox for large distribution problems.     

State-dependent swap strategies and automatic reduction of number of temperatures in adaptive parallel tempering algorithm

In this paper we present extensions to the original adaptive Parallel Tempering algorithm. Two different approaches are presented. In the first one we introduce state-dependent strategies using current information to perform a swap step. It encompasses a wide family of potential moves including the standard one and Equi-Energy type move, without any loss in tractability. In the second one, we introduce online trimming of the number of temperatures. Numerical experiments demonstrate the effectiveness of the proposed method.     

Sample Path Asymmetries in Non‐Gaussian Random Processes

We tackle an important although rarely addressed question of accounting for a variety of asymmetries frequently observed in stochastic temporal/spatial records. First, we review some measures intending to capture such asymmetries that have been introduced on various occasions in the past and then propose a family of measures that is motivated by Rice's formula for crossing level distributions of the slope. We utilize those asymmetry measures to demonstrate how a class of second‐order models built on the skewed Laplace distributions can account for sample path asymmetries. It is shown that these models are capable of mimicking not only distributional skewness but also more complex geometrical asymmetries in the sample path such as tilting, front‐back slope asymmetry and time irreversibility. Simple moment‐based estimation techniques are briefly discussed to allow direct application to modelling and fitting actual records.     

Assessment of frailty syndrome using Edmonton frailty scale in Polish elderly sample

The aim of the study was to assess the incidence and severity of the frailty syndrome assessed with the Edmonton Frailty Scale. This is a cross-sectional study conducted among 382 patients (236 men and 146 women, mean age 71.9?years). The Edmonton Frailty Scale was administered during the patient’s admission to the hospital. The Polish adaptation was performed using the standard methodology. The Cronbach’s alpha coefficient for the whole Edmonton Frailty Scale was 0.709. The mean correlation between positions and the overall result was r?=?0.180. There were no statistically significant differences between women and men in the area of Edmonton Frailty Scale mean score (p?70?years than for those?<70?years (p?相似文献