Asymmetric exchange between populations differing in habitat quality: A metapopulation study on the citril finch

The citril finch ( Serinus citrinella ) is a Cardueline finch restricted to the high mountains of western Europe. Since 1991 we have captured-recaptured about 6000 birds in two contrasting subpopulations located on the same mountain but separated by 5 km in distance. Citril finches, at the north-facing locality (La Vansa), rely more on Pine trees ( Pinus uncinata ) as their main food source, than birds at the south-facing locality (La Bofia), which rely more on herb seeds, which are of lower energetic content. Birds at La Vansa had higher body mass and fat score than those at La Bofia, suggesting that La Vansa was a site of higher-quality than La Bofia. By the use of a metapopulation approach and multistate models, we found that citril finches at the high-quality locality (La Vansa) showed higher survival rates than those at the low-quality one (La Bofia) (Vansa adults: φ = 0.42 - 0.04, juveniles: φ = 0.34 - 0.05; Bofia adults: φ = 0.35 - 0.04, juveniles: φ = 0.28 - 0.05). Dispersal was also asymmetric and higher for juvenile birds, with movement rates for juvenile citril finches from the low-quality to the higher-quality locality (Bofia to Vansa: é = 0.38 - 0.10) higher than the reverse (Vansa to Bofia: é = 0.09 - 0.03). We also investigated time-specific factors (e.g. meteorological data and fructification rate of Pinus ) as potential predictors of overall mortality and dispersal patterns. The results do not allow strong conclusions regarding the impact of these factors on survival and movement rates. Patterns of movement found in the Citril Finch between localities document a new model for the dispersal of species from low to high quality habitats, which we label of 'sources and pools'. This contrasts with currently accepted models of 'sources and sinks', in which movement is from high to low quality habitats, and 'Ideal Free Distributions', in which there is a balanced dispersal between habitats of different quality.     

Digitalisierung der Arbeit: Konsequenzen für Führung und Zusammenarbeit

In this paper, we focus on the characteristics and requirements of digital leadership and cooperation when teams are working on complex and dynamic project tasks, and cooperation is mediated by modern information and communication technology. Based on current research results we discuss the question, whether the thesis can be supported that leadership of complex digital teamwork can only be successful if leadership functions are delegated to the team and personal leadership is complemented by structural leadership. Despite many ambiguous research results regarding the effects of digital leadership current findings seem to support that more shared leadership in self-managing project teams seems to be helpful for team performance.     

On Stalnaker's Notion of Strong Rationalizability and Nash Equilibrium in Perfect Information Games

Counterexamples to two results by Stalnaker (Theory and Decision, 1994) are given and a corrected version of one of the two results is proved. Stalnaker's proposed results are: (1) if at the true state of an epistemic model of a perfect information game there is common belief in the rationality of every player and common belief that no player has false beliefs (he calls this joint condition strong rationalizability), then the true (or actual) strategy profile is path equivalent to a Nash equilibrium; (2) in a normal-form game a strategy profile is strongly rationalizable if and only if it belongs to C , the set of profiles that survive the iterative deletion of inferior profiles.     

Web-Based Accountability Practices in Non-profit Organizations: The Case of National Museums

Stakeholder theory posits that accountability systems depend on the strength and the number of their stakeholders. This paper aims to analyze the empirical validity of stakeholder theory, focusing on accountability systems in the museum sector. Based on Wikipedia resources, we have selected all of the “National Museums” (134 museums) in the major developed countries: Australia, Canada, France, Germany, Italy, the United Kingdom, and the US. After we control for type of activity (art or other), cost per visitor and country, the results of an OLS multivariate model show that size of the museum, which is assumed to represent the strength and number of stakeholders, and the amount of funds received, which represents the power of a particularly salient category of stakeholders (donors), are the two main determinants of the accountability level. We conclude that accountability, in the absence of shareholders, is driven by the number and the power of different stakeholders, validating the stakeholder theory.     

Measuring risk aversion with lists: a new bias

Various experimental procedures aimed at measuring individual risk aversion involve a list of pairs of alternative prospects. We first study the widely used method by Holt and Laury (Am Econ Rev 92(5):1644–1655, 2002), for which we find that the removal of some items from the lists yields a systematic decrease in risk aversion and scrambles the ranking of individuals by risk aversion. This bias, that we call embedding bias, is quite distinct from other confounds that have been previously observed in the use of the HL method. It may be related to empirical phenomena and theoretical developments where better prospects increase risk aversion. Nevertheless, we also find that the more recent elicitation method due to Abdellaoui et al. (Theory Decis 71:63–80, 2011), also based on lists but using only one and the same probability in the list, does not display any statistically significant bias when the corresponding items of the list are removed. Our results suggest that methods other than the popular HL one may be preferable for the measurement of risk aversion.     

CLASS SIZE AND CLASS HETEROGENEITY

We study how class size and class composition affect the academic and labor market performance of college students, two crucial policy questions given the secular increase in college enrollment. Our identification strategy relies on the random assignment of students to teaching classes. We find that a one standard deviation increase in class‐size results in a 0.1 standard deviation deterioration of the average grade. Further, the effect is heterogeneous as it is stronger for males and lower income students. Also, the effects of class composition in terms of gender and ability appear to be inverse U‐shaped. Finally, a reduction of 20 students (one standard deviation) in one’s class size has a positive effect on monthly wages of about €80 ($115) or 6% over the average.     

Regional now- and forecasting for data reported with delay: toward surveillance of COVID-19 infections

AStA Advances in Statistical Analysis - Governments around the world continue to act to contain and mitigate the spread of COVID-19. The rapidly evolving situation compels officials and executives...