Konformit?t durch Herdenverhalten

The adjustment of one??s own actions to the behavior of others offers an inexpensive alternative to self-reliant reasoning. Thus, from a sociological perspective conformity mirrors informative social influences. First, a basic model of social herding is presented, which describes initial conditions and consequences of informational imitation. Central implications of the model are then tested using process-produced data from the German book market (2001?C2006). While the release of public information as well as announcements by opinion leaders trigger conformity under imperfect information, these stimuli show no effects when the general availability of information is improved. Moreover, the availability of information among readers determines the quality of emerging bestsellers. Altogether, the model of herd behavior proves useful in understanding demand processes in book markets.     

Links between childhood physical abuse and intimate partner aggression: the mediating role of anger expression

Research linking childhood physical abuse (CPA) and adult intimate partner aggression (IPA) has focused on individuals without sufficient attention to couple processes. In this study, 109 couples reported on histories of CPA, IPA, and anger expression. Actor-partner interdependence model (APIM) was used to examine links between CPA and revictimization and perpetration of IPA, with anger suppression as a potential mediator. Women's CPA histories were associated with more physical aggression towards and more revictimization by partners. Men's CPA histories were only associated at the trend level with their revictimization. Anger suppression fully mediated the link between women's CPA and both revictimization and perpetration of IPA. Findings suggest that women with CPA histories are more prone to suppress anger, which leaves them at greater risk for revictimization and perpetration of IPA.     

Condom Use Trajectories in Adolescence and the Transition to Adulthood: The Role of Mother and Father Support

Few studies have investigated how mother and father support differ on predicting youths' sexual risk behavior. We therefore examined the influence of parental support on condom use trajectories and its correlates in a predominantly African American sample [(N=627; 53% female; M = 14.86 years (SD=. 64)] from adolescence to young adulthood. We used hierarchical growth curve modeling to examine the relationship between condom use, substance use, psychological distress and parental support prospectively. We found that consistent condom use decreased over time and was associated negatively with psychological distress and substance use. Furthermore, both maternal and paternal support were associated with more condom use over time. We discuss the implications of our findings for HIV prevention programs.     

Movement-in-depth, cognitive impairment, and crash risk

In this study, 243 cognitively intact and cognitively impaired older participants' movement-in-depth (looming) abilities were assessed using a portable device that we had previously developed in our laboratory. Results indicated normative relationships between looming ability and age, looming ability and driving violation records, and age and driving violation records. Findings also confirmed the validity and reliability of the measurements taken with the device. In conclusion, this device may be useful for identifying drivers at risk for rear-end collisions, developing effective training interventions, and creating fair and valid driver licensing tests.     

An Overview of and Rationale for Changes Proposed for Pathological Gambling in DSM-5

The fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) is scheduled for publication in 2013. It will include several changes to the diagnosis of pathological gambling: the name of the disorder will be altered, the threshold for diagnosis will decrease, and one criterion will be removed. This paper reviews the rationale for these changes and addresses how they may impact diagnosis and treatment of the disorder, as well as potential for future research in the field.     

COST INCREASES DUE TO DEMAND UNCERTAINTY IN MRP LOT SIZING

This paper analyzes the cost increases due to demand uncertainty in single-level MRP lot sizing on a rolling horizon. It is shown that forecast errors have a tremendous effect on the cost effectiveness of lot-sizing techniques even when these forecast errors are small. Moreover, the cost differences between different techniques become rather insignificant in the presence of forecast errors. Since most industrial firms face demand uncertainty to some extent, our findings may have important managerial implications. Various simulation experiments give insight into both the nature and the magnitude of the cost increases for different heuristics. Analytical results are developed for the constant-demand case with random noise and forecasting by exponential smoothing. It is also shown how optimal buffers can be obtained by use of a simple model. Although the analysis in this paper is restricted to simplified cases, the results merit further consideration and study. This paper is one of the first to inject forecast errors into MRP lot-sizing research. As such it attempts to deal with one of the major objections against the practical relevance of previous research in this area.     

Ratio-Scale Measurement with Intransitivity or Incompleteness: The Homogeneous Case

In the homogeneous case of one-dimensional objects, we show that any relation that is positive and homothetic can be represented by a ratio-scale and a unique and constant biasing factor. This factor may favor or disfavor the preference for an object over another. In the first case, preferences are complete but not transitive and an object may be preferred even when its value is lower. In the second case, preferences are asymmetric and transitive but not negatively transitive and it may not be sufficient for an object to have a greater value to be preferred. In this manner, the biasing factor reflects the extent to which preferences may depart from a maximization process.     

Bootstrap and permutation rank tests for proportional hazards under right censoring

We address the testing problem of proportional hazards in the two-sample survival setting allowing right censoring, i.e., we check whether the famous Cox model is underlying. Although there are many test proposals for this problem, only a few papers suggest how to improve the performance for small sample sizes. In this paper, we do exactly this by carrying out our test as a permutation as well as a wild bootstrap test. The asymptotic properties of our test, namely asymptotic exactness under the null and consistency, can be transferred to both resampling versions. Various simulations for small sample sizes reveal an actual improvement of the empirical size and a reasonable power performance when using the resampling versions. Moreover, the resampling tests perform better than the existing tests of Gill and Schumacher and Grambsch and Therneau . The tests’ practical applicability is illustrated by discussing real data examples.