Constructing robust crew schedules with bicriteria optimization

Optimization‐based computer systems are used by many airlines to solve crew planning problems by constructing minimal cost tours of duty. However, today airlines do not only require cost effective solutions, but are also very interested in robust solutions. A more robust solution is understood to be one where disruptions in the schedule (due to delays) are less likely to be propagated into the future, causing delays of subsequent flights. Current scheduling systems based solely on cost do not automatically provide robust solutions. These considerations lead to a multiobjective framework, as the maximization of robustness will be in conflict with the minimization of cost. For example crew changing aircraft within a duty period is discouraged if inadequate ground time is provided. We develop a bicriteria optimization framework to generate Pareto optimal schedules for the domestic airline. A Pareto optimal schedule is one which does not allow an improvement in cost and robustness at the same time. We developed a method to solve the bicriteria problem, implemented it and tested it with actual airline data. Our results show that considerable gain in robustness can be achieved with a small increase in cost. The additional cost is mainly due to an increase in overnights, which allows for a reduction of the number of aircraft changes. Copyright © 2003 John Wiley & Sons, Ltd.     

Working with Research Integrity—Guidance for Research Performing Organisations: The Bonn PRINTEGER Statement

This document presents the Bonn PRINTEGER Consensus Statement: Working with Research Integrity—Guidance for research performing organisations. The aim of the statement is to complement existing instruments by focusing specifically on institutional responsibilities for strengthening integrity. It takes into account the daily challenges and organisational contexts of most researchers. The statement intends to make research integrity challenges recognisable from the work-floor perspective, providing concrete advice on organisational measures to strengthen integrity. The statement, which was concluded February 7th 2018, provides guidance on the following key issues:

1. § 1.
   Providing information about research integrity
    
2. § 2.
   Providing education, training and mentoring
    
3. § 3.
   Strengthening a research integrity culture
    
4. § 4.
   Facilitating open dialogue
    
5. § 5.
   Wise incentive management
    
6. § 6.
   Implementing quality assurance procedures
    
7. § 7.
   Improving the work environment and work satisfaction
    
8. § 8.
   Increasing transparency of misconduct cases
    
9. § 9.
   Opening up research
    
10. § 10.
    Implementing safe and effective whistle-blowing channels
     
11. § 11.
    Protecting the alleged perpetrators
     
12. § 12.
    Establishing a research integrity committee and appointing an ombudsperson
     
13. § 13.
    Making explicit the applicable standards for research integrity
     

     

Biases in multilevel analyses caused by cluster-specific fixed-effects imputation

When datasets are affected by nonresponse, imputation of the missing values is a viable solution. However, most imputation routines implemented in commonly used statistical software packages do not accommodate multilevel models that are popular in education research and other settings involving clustering of units. A common strategy to take the hierarchical structure of the data into account is to include cluster-specific fixed effects in the imputation model. Still, this ad hoc approach has never been compared analytically to the congenial multilevel imputation in a random slopes setting. In this paper, we evaluate the impact of the cluster-specific fixed-effects imputation model on multilevel inference. We show analytically that the cluster-specific fixed-effects imputation strategy will generally bias inferences obtained from random coefficient models. The bias of random-effects variances and global fixed-effects confidence intervals depends on the cluster size, the relation of within- and between-cluster variance, and the missing data mechanism. We illustrate the negative implications of cluster-specific fixed-effects imputation using simulation studies and an application based on data from the National Educational Panel Study (NEPS) in Germany.     

Simultaneous motor demands affect decision making under objective risk

Previous studies on factors influencing decision making focused on the effects of additional cognitive load, stress, psychological disorders, and the process of aging. The potential effects of simultaneously performing motor demands have been neglected, so far. However, previous motor / cognitive dual-task studies provide evidence for both negative as well as facilitating effects of simultaneously performing cognitive and motor tasks. The study at hand, aimed to investigate the effects of decision making under objective risk while performing additional motor demands. Seventy-two participants ranging from 18 to 30 years performed the Game of Dice Task either while sitting or while standing on one leg. Participants were asked to put similar effort on the decision task and the motor demand. The results revealed a significant main effect for “choice”, as well as a significant interaction of “choice”?×?“group”. Participants standing on one leg more frequently selected the most disadvantageous choice (one single number), whereas the “sitting group” most often selected the advantageous combination of four numbers. The findings are discussed under the aspects of executive functions, working memory, stress, somatic markers and the dual-process theory.     

Response-retrieval and negative priming

The existence of across-notation automatic numerical processing of two-digit (2D) numbers was explored using size comparisons tasks. Participants were Arabic speakers, who use two sets of numerical symbols—Arabic and Indian. They were presented with pairs of 2D numbers in the same or in mixed notations. Responses for a numerical comparison task were affected by decade difference and unit-decade compatibility and global distance in both conditions, extending previous findings with Arabic digits (Nuerk, Weger, & Willmes, 2001). Responses for a physical comparison task were affected by congruency with the numerical size, as indicated by the size congruency effect (SiCE). The SiCE was affected by unit-decade compatibility but not by global distance, thus suggesting that the units and decades digits of the 2D numbers, but not the whole number value were automatically translated into a common representation of magnitude. The presence of similar results for same- and mixed-notation pairs supports the idea of an abstract representation of magnitude.     

Reminders of an agentic ingroup buffer disease uncontrollability

Chronic illness has negative impacts beyond those on physical health. In particular, because it is often experienced as uncontrollable, chronic illness might reduce people's general sense of personal control and, subsequently, personal well-being. Drawing on recent theory and research, we proposed and tested in four experiments (N_total = 1323) a potential buffer to these negative effects: thinking about an agentic social ingroup in one's life. In Study 1, patients suffering from a chronic illness that was either high or low in medical disease controllability were asked either to think about an agentic ingroup or a personal issue. Low perceived disease-related control was associated with low perceived personal control only when participants' personal self, but not when their ingroup, was salient. In three follow-up vignette studies, we asked participants to take the perspective of a person who suffered from a health problem of low medical disease controllability and attended a self-help group that was described as either high or low in agency. The findings supported the predicted buffering effect: participants who reflected on a target suffering from a low control disease thought that the target would experience more personal control when the agentic (vs. the nonagentic) self-help group was salient. These findings suggest ingroups can serve as a source of personal control in the context of health-related threats to the extent that they are perceived as agentic. Thus, focusing on agentic properties of (health-related) ingroups might be a promising novel strategy when designing effective group-based interventions to cope with chronic illness.     

Causal attributions of obese men and women in genetic testing: Implications of genetic/biological attributions1

The present study sought to investigate genetic/biological attributions of obesity, their associations with a predisposition to obesity and their crossectional and longitudinal implications for weight regulation in obese individuals presenting for genetic testing and counselling. A total of 421 obese men and women underwent psychological and anthropometric assessment and a mutation screen of the melanocortin-4 receptor gene. At study entry, women revealed more genetic/biological attributions than men on the Revised Illness Perception Questionnaire adapted to obesity (86.2% versus 59.7%). Genetic/biological attributions of obesity were associated in both sexes with a family history of obesity, assessed through Stunkard's Figure Rating Scale. In both sexes, genetic/biological attributions were unrelated to weight regulation beliefs and behaviour (i.e. self-efficacy, controllability beliefs, restrained eating and physical activity), assessed through standardised questionnaires or interview at baseline and at six-month follow-up. In addition, causal attributions and weight regulation beliefs and behaviour were not predictive of body mass index at six-month follow-up. Overall, the results indicate that causal attributions of obesity to genetic/biological factors in obese individuals presenting for genetic screening and counselling are crossectionally and longitudinally unrelated to weight regulation and longer-term weight outcome. Those who attribute their obesity to genetic/biological factors likely have a familial obesity risk.     

Decision-making,cognitive functions,impulsivity, and media multitasking expectancies in high versus low media multitaskers

In several studies, individuals who reported to frequently multitask with different media displayed reduced cognitive performance, for example in fluid intelligence and executive functioning. These cognitive functions are relevant for making advantageous decisions under both objective risk (requiring reflection and strategical planning) and ambiguous risk (requiring learning from feedback). Thus, compared to low media multitaskers (LMMs), high media multitaskers (HMMs) may perform worse in both types of decision situations. The current study investigated HMMs and LMMs in a laboratory setting with the Game of Dice Task (GDT; objective risk), the Iowa Gambling Task (IGT; ambiguous risk), various tests quantifying cognitive functions (logical reasoning, working memory, information processing, general executive functions), and self-report measures of impulsivity, media multitasking expectancies, and problematic Internet use. From 182 participants, 25 HMMs and 19 LMMs were identified using the Media Multitasking Index. Results show that HMMs compared to LMMs performed weaker on the IGT but not on the GDT. Furthermore, HMMs had slightly decreased performance in tests of logical reasoning and working memory capacity. HMMs tended to increased information processing speed but this difference was not significant. Furthermore, HMMs have more positive expectancies regarding media multitasking and reported higher tendencies toward problematic Internet use. HMMs and LMMs did not differ significantly with respect to impulsivity and executive functions. The results give a first hint that HMMs may have difficulties in decision-making under ambiguous but not under objective risk. HMMs may be more prone to errors in tasks that require feedback processing. However, HMMs appear not to be impaired in aspects of long-term strategic decision-making.

     

Effect of delay on children's delay-execute prospective memory performance

To date, little work has been done investigating prospective memory in children, particularly using a delay-execute paradigm. Two experiments were conducted to investigate this issue with children aged 5–11 years. While playing a computer driving game, children's ability to carry out a delayed intention either immediately a target cue appeared or after an additional delay, was assessed. These findings supported the few previous studies in this area by showing that preschool children are able to perform event-based prospective memory tasks. The results also extended these findings by demonstrating the impact of briefly delaying the execution of a retrieved intention, and revealing that there were important improvements in prospective memory performance from early to late childhood. The suggestion is made that executive resources may be responsible for this pattern of performance.     

Implicit interpretation biases affect emotional vulnerability: a training study

Cognitive theories of emotion propose that the interpretation of emotion-eliciting situations crucially shapes affective responses. Implicit or automatic biases in these interpretations may hinder emotion regulation and thereby increase risk for the onset and maintenance of psychological disorders. In this study, participants were randomly assigned to a positive or negative interpretation bias training using ambiguous social scenarios. After the completion of the training, a stress task was administered and changes in positive and negative affect and self-esteem were assessed. The results demonstrate that the interpretation bias training was successful in that participants exhibited a tendency to interpret novel scenarios in accordance with their training condition. Importantly, the positive training condition also had a protective effect on self-esteem. Participants in this condition did not exhibit a decrease in self-esteem after the stress task, whereas participants in the negative condition did. These results demonstrate that implicit cognitive biases can be trained and that this training affects self-esteem. Implications of these findings for research on psychopathology and emotion regulation are discussed.