Publications of Michael Schyns
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See detailExperimental investigation of decision-making processes in daily physically active behaviors using a virtual reality set-up
Ruffault, Alexis ULiege; Cloes, Marc ULiege; Schyns, Michael ULiege et al

Poster (2018, August)

Background: Energy expenditure provided by physical activity (PA) can be significantly increased by daily behaviors (stair use, walking). However, factors from the environment, and motivational and ... [more ▼]

Background: Energy expenditure provided by physical activity (PA) can be significantly increased by daily behaviors (stair use, walking). However, factors from the environment, and motivational and volitional processes, tend to impact the decisions when an active solution (stairs) is available at the same time as an inactive solution (elevator). The aim of this study is to identify the decision-making processes implicated in daily PA when time and effort to reach an objective (e.g., a meeting) vary. Methods: 150 healthy adults will be randomized to one of three experiments after filling out questionnaires measuring habits regarding PA, motivational, and volitional factors of PA adoption. Experiment 1 is a first-person 3D interactive movie where 3 actors are waiting at the point-of-decision, where peers’ behaviors and availability of the inactive solution vary. Experiment 2 is a virtual replication of a business school, where previous knowledge of the building and disposition of the stairs (hidden/visible) vary. Experiment 3 is a virtual modified version of the business school where a stairwell and an escalator provide access to the first floor, using implicit (steps on the floor) and explicit (motivational messages) as point-of-decision prompts. Expected results: Results will be analyzed in line with the integrated behavior change model (Hagger & Chatzisarantis, 2014) and the naturalistic decision-making theory (Klein, 2015). Current stage of work: Participants will be contacted for experimentations from February to June 2018. Discussion: Real time decision-making processes will be linked to processes of change regarding PA, allowing for recommendations for future interventional designs. [less ▲]

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See detailModeling competition among airline itineraries
Lurkin, Virginie ULiege; Garrow, Laurie A.; Higgins, Matthew J. et al

in Transportation Research. Part A, Policy and Practice (2018), 113

Discrete choice models are commonly used to forecast the probability an airline passenger chooses a specific itinerary. In a prior study, we estimated an itinerary choice model based on a multinomial ... [more ▼]

Discrete choice models are commonly used to forecast the probability an airline passenger chooses a specific itinerary. In a prior study, we estimated an itinerary choice model based on a multinomial logit specification that corrected for price endogeneity. In this paper, we extend the analysis to include inter-itinerary competition along three dimensions: nonstop versus connecting level of service, carrier, and time of day using nested logit (NL) and ordered generalized extreme value (OGEV) models. To the best of our knowledge, these are the first NL and OGEV itinerary choice models to correct for price endogeneity. Despite the many structural changes that have occurred in the airline industry, our results are strikingly similar to models estimated more than a decade ago. These results are important because it suggests that customer preferences, on average, have been stable over time and are similar across distribution channels. The stability in inter-itinerary competition patterns provides an important practical implication for airlines, namely it reduces the need to frequently update the parameter estimates for these models. [less ▲]

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See detailA tailored two-phase constructive heuristic for the three-dimensional Multiple Bin Size Bin Packing Problem with transportation constraints
Paquay, Célia ULiege; Limbourg, Sabine ULiege; Schyns, Michael ULiege

in European Journal of Operational Research (2018), 267(1), 52-64

This paper considers the three-dimensional Multiple Bin Size Bin Packing Problem which consists in packing a set of cuboid boxes into containers of various shapes with minimising unused space. The problem ... [more ▼]

This paper considers the three-dimensional Multiple Bin Size Bin Packing Problem which consists in packing a set of cuboid boxes into containers of various shapes with minimising unused space. The problem is extended to air cargo where bins are Unit Load Devices, especially designed for fitting in aircraft. We developed a fast constructive heuristic able to manage the different constraints met in transportation. The heuristic is split into two distinct phases. The first phase deals with the packing of boxes into identical bins using an extension of the Extreme Points. During this phase, the fragility, stability and orientations of the boxes are taken into account as well as the special shape of the bins and their weight capacity. The second phase takes into account the multiple types of available bins. If necessary, the best found loading pattern is finally enhanced with respect to weight distribution in a post processing. After parametrisation, computational experiments have been performed on data sets especially designed for this application. The heuristic requires really short computational times to achieve promising results. [less ▲]

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See detailUNITÉ DE RECHERCHE LIÈGE – QUÉBEC SUR LE NUMÉRIQUE EN SANTÉ GLOBALE, EN ENSEIGNEMENT ET EN FORMATION CONTINUE UNIVERSITAIRE
Etienne, Anne-Marie ULiege; Bouchard, Stéphane; Billen, Roland ULiege et al

Speech/Talk (2018)

The promoters of the project are the University of Liège, represented by Rector Albert CORHAY, and the Université du Québec en Outaouais, represented by Rector Denis HARRISSON. The academic leaders are ... [more ▼]

The promoters of the project are the University of Liège, represented by Rector Albert CORHAY, and the Université du Québec en Outaouais, represented by Rector Denis HARRISSON. The academic leaders are: for the University of Liège, Anne-Marie ETIENNE, Professor and Vice-Dean for Education and for the Université du Québec en Outaouais, Stéphane BOUCHARD, Professor and Holder of the Canada Research Chair in Cyberpsychology Clinical. As part of the strategic plan of the University of Liège, the global project of digital use is part of two major societal challenges namely education and digital technology, health and society. This global digital use project focuses on teaching, research and citizenship missions and on the individual, his community and the society in which he lives. The specific objectives of this collaboration are to (1) Develop support tools for the university community, (2) Offer awakening or support workshops in complementarity with the community and (3) Ensure a monitoring mandate and knowledge sharing. Exchanges between the two partners can be carried out along different axes, namely initial training and continuing training; the development of joint research projects or mobility through exchanges of students, teachers, researchers, technicians and experts. [less ▲]

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See detailAssessing and predicting review helpfulness: Critical review, open challenges and research agenda
Hoffait, Anne-Sophie ULiege; Ittoo, Ashwin ULiege; Schyns, Michael ULiege

E-print/Working paper (2018)

The issues of determining what makes a customer review helpful and how to predict review helpfulness have received significant attention in recent years. However, the current literature is highly ... [more ▼]

The issues of determining what makes a customer review helpful and how to predict review helpfulness have received significant attention in recent years. However, the current literature is highly heterogeneous with contradictory findings. We critically synthesize extant literature and identify factors responsible for these contradictions which we classify into four dimensions, viz. datasets, features, approach and review helpfulness operationalization, and clarify the prevailing confusion. We highlight research gaps, and propose novel research directions to bridge them and to advance the state-of-the-art. We provide resources such as synthetic tables, which summarize past research and develop a (future) research roadmap. These resources not only provide a concise overview of current research, but also illustrate its heterogeneity and serve as a valuable basis to ground future research. [less ▲]

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See detailMIP-based constructive heuristics for the three-dimensional Bin Packing Problem with transportation constraints
Paquay, Célia ULiege; Limbourg, Sabine ULiege; Schyns, Michael ULiege et al

in International Journal of Production Research (2018), 56(4), 1581-1592

This article is about seeking a good feasible solution in a reasonable amount of computation time to the three-dimensional Multiple Bin Size Bin Packing Problem (MBSBPP). The MBSBPP studied considers ... [more ▼]

This article is about seeking a good feasible solution in a reasonable amount of computation time to the three-dimensional Multiple Bin Size Bin Packing Problem (MBSBPP). The MBSBPP studied considers additional constraints encountered in real world air transportation situations, such as cargo stability and the particular shape of containers. This MBSBPP has already been formulated as a Mixed Integer linear Programming problem, but as yet only poor results have been achieved for even fairly small problem sizes. The goal of the work this paper describes is to develop heuristics that are able to quickly provide good initial feasible solutions for the MBSBPP. Three methodologies are considered, which are based on the decomposition of the original problem into easier subproblems: the matheuristics Relax-and-Fix, Insert-and-Fix and Fractional Relax-and-Fix. They have been parametrised on real data sets and then compared to each other. In particular, two of these techniques show promising results in reasonable computational times. [less ▲]

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See detailSpecial issue: Twelfth Workshop on Models and Algorithms for Planning and Scheduling Problems (MAPSP 2015)
Crama, Yves ULiege; Goossens, Dries; Leus, Roel et al

in Journal of Scheduling (2017), 20(6), 543-711

This special issue of the Journal of Scheduling contains ten papers presented at the Twelfth Workshop on Models and Algorithms for Planning and Scheduling Problems (MAPSP 2015), held from June 8 to June ... [more ▼]

This special issue of the Journal of Scheduling contains ten papers presented at the Twelfth Workshop on Models and Algorithms for Planning and Scheduling Problems (MAPSP 2015), held from June 8 to June 12, 2015, in La Roche-en-Ardenne, Belgium. [less ▲]

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See detailTeaching with VR. Développer des environnements virtuels pour l'enseignement en sciences humaines
Billen, Roland ULiege; Dozo, Björn-Olav ULiege; Etienne, Anne-Marie ULiege et al

Conference (2017, November 23)

Présentation du projet Teaching with VR, qui associe des enseignants-chercheurs de 4 facultés pour développer des environnements en réalité virtuelle au service de l'enseignement en sciences humaines ... [more ▼]

Présentation du projet Teaching with VR, qui associe des enseignants-chercheurs de 4 facultés pour développer des environnements en réalité virtuelle au service de l'enseignement en sciences humaines. Trois environnements sont montrés, qui peuvent être déclinés pour différentes disciplines (psychologie, architecture, marketing, etc.), en fonction de dispositifs ajoutés aux environnements. [less ▲]

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See detailTeaching with VR. Développer des environnements virtuels au service de l’enseignement en sciences humaines et sociales
Billen, Roland ULiege; Dozo, Björn-Olav ULiege; Etienne, Anne-Marie ULiege et al

Conference given outside the academic context (2017)

L’élaboration d’environnements de réalité virtuelle requiert des compétences pluridisciplinaires. A l’ULiège, un groupe d’enseignants-chercheurs, le groupe « Teaching with VR », ont mis en commun leurs ... [more ▼]

L’élaboration d’environnements de réalité virtuelle requiert des compétences pluridisciplinaires. A l’ULiège, un groupe d’enseignants-chercheurs, le groupe « Teaching with VR », ont mis en commun leurs savoir-faire et expériences spécifiques sur la réalité virtuelle et les environnements en 3 dimensions afin de développer plusieurs environnements supports à différents enseignements dans le secteur des sciences humaines (psychologie, marketing, logistique, archéologie du bâti, didactique de l’histoire, game design, game studies…). [less ▲]

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See detailEarly Detection of University Students with Potential Difficulties
Hoffait, Anne-Sophie ULiege; Schyns, Michael ULiege

in Decision Support Systems (2017), 101

Using data mining methods, this paper presents a new means of identifying freshmen's profiles likely to face major difficulties to complete their first academic year. Academic failure is a relevant issue ... [more ▼]

Using data mining methods, this paper presents a new means of identifying freshmen's profiles likely to face major difficulties to complete their first academic year. Academic failure is a relevant issue at a time when post-secondary education is ever more critical to economic success. We aim at early detection of potential failure using student data available at registration, i.e. school records and environmental factors, with a view to timely and efficient remediation and/or study reorientation. We adapt three data mining methods, namely random forest, logistic regression and artificial neural network algorithms. We design algorithms to increase the accuracy of the prediction when some classes are of major interest. These algorithms are context independent and can be used in different fields. Real data pertaining to undergraduates at the University of Liège (Belgium), illustrates our methodology. [less ▲]

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See detailEarly detection of university students with potential difficulties
Hoffait, Anne-Sophie ULiege; Schyns, Michael ULiege

Conference (2017, July)

Using data mining methods, this paper presents a new means of identifying freshmen's profiles likely to face major difficulties to complete their first academic year. We aim at early detection of ... [more ▼]

Using data mining methods, this paper presents a new means of identifying freshmen's profiles likely to face major difficulties to complete their first academic year. We aim at early detection of potential failure using student data available at registration, i.e. school records and environmental factors, with a view to timely and efficient remediation and/or study reorientation. We adapt three data mining methods, namely random forest, logistic regression and artificial neural network algorithms. We design algorithms to increase the accuracy of the prediction when some classes are of major interest. These algorithms are context independent and can be used in different fields. They rely on a dynamic split of the observations into subclasses during the training process, so as to maximize an accuracy criterion. Four classes are so built: high risk of failure, risk of failure, expected success or high probability of success. Real data pertaining to undergraduates at the University of Liège (Belgium), illustrates our methodology. With our approach, we are now able to identify with a high rate of confidence (90%) a subset of 12.2% of students facing a very high risk of failure, almost the quadruple of those identified with a non-dynamic approach. By testing some confidence levels, our approach makes it possible to rank the students by levels of risk and a sensitivity analysis allows us to find out why some students are likely to encounter difficulties. [less ▲]

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See detailAccounting for Price Endogeneity in Airline Itinerary Choice Models: An Application to Continental U.S. Markets
Lurkin, Virginie ULiege; Garrow, Laurie; Higgins, Matthew et al

in Transportation Research. Part A, Policy and Practice (2017), 100

Network planning models, which forecast the profitability of airline schedules, support many critical decisions, including equipment purchase decisions. Network planning models include an itinerary choice ... [more ▼]

Network planning models, which forecast the profitability of airline schedules, support many critical decisions, including equipment purchase decisions. Network planning models include an itinerary choice model which is used to allocate air total demand in a city pair to different itineraries. Multinomial logit (MNL) models are commonly used in practice and capture how individuals make trade-offs among different itinerary attributes; however, none that we are aware of account for price endogeneity. This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables. We estimate our models using database of more than 3 million tickets provided by the Airlines Reporting Corporation. Results based on Continental U.S. markets for May 2013 departures show that models that fail to account for price endogeneity overestimate customers’ value of time and result in biased price estimates and incorrect pricing recommendations. The size and comprehensiveness of our database allows us to estimate highly refined departure time of day preference curves that account for distance, direction of travel, the number of time zones traversed, departure day of week and itinerary type (outbound, inbound or one-way). These time of day preference curves can be used by airlines, researchers, and government organizations in the evaluation of different policies such as congestion pricing. [less ▲]

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See detailInstances for the 3D Multiple Bin Size Bin Packing Problem
Paquay, Célia ULiege; Limbourg, Sabine ULiege; Schyns, Michael ULiege

Textual, factual or bibliographical database (2017)

The subject of this work is to solve the problem of packing a set of shipments (various cuboid boxes) into containers of various shapes without wasting loading space. All the boxes have to be loaded and ... [more ▼]

The subject of this work is to solve the problem of packing a set of shipments (various cuboid boxes) into containers of various shapes without wasting loading space. All the boxes have to be loaded and few are identical. As it is the case for all the packing problems, the packing has to satisfy geometry constraints: the items cannot overlap and have to lie entirely inside the bins. The richness of our application is to manage additional and common constraints: the bin weight capacity, the rotations of the boxes, the stability and the fragility of the boxes and the uniformity of the weight distribution inside the ULDs. The last constraint is crucial in air transportation: when ULDs are packed inside the airplane, the centre of gravity is computed assuming each ULD has a centre of gravity close to the geometrical centre of its basis. This type of constraints can be adapted to road transportation for the axle weight limits, which plays a key role since the weigh-in-motion systems become more common. [less ▲]

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See detailA best fit heuristic for the three-dimensional Bin Packing Problem with practical constraints from an air transportation application
Paquay, Célia ULiege; Limbourg, Sabine ULiege; Schyns, Michael ULiege

in Proceedings of the BIVEC-GIBET Transport Research Days 2017 (2017)

This work considers the three-dimensional Multiple Bin Size Bin Packing Problem which consists in packing a set of cuboid boxes into containers of various shapes, while minimising unused space. The aim of ... [more ▼]

This work considers the three-dimensional Multiple Bin Size Bin Packing Problem which consists in packing a set of cuboid boxes into containers of various shapes, while minimising unused space. The aim of the present work is to find good initial solutions in short computational times. In this purpose, a fast best fit heuristic able to manage the different constraints to be met in transportation is developed. The heuristic is split into two distinct phases. The first phase deals with the packing of boxes into identical bins using an extension of the Extreme Points rule. During this phase, the fragility, stability and orientation of the boxes are taken into account, as well as the special shape of the bins and their weight capacity. The second phase considers the multiple types of available bins. If necessary, the best loading pattern identified is enhanced with respect to weight distribution in post processing. After parametrisation, computational experiments are performed on data sets specially designed for this application. The heuristic requires very short computational times to achieve promising results. [less ▲]

Detailed reference viewed: 121 (3 ULiège)
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See detailEarly detection of university students in potential difficulty
Hoffait, Anne-Sophie ULiege; Schyns, Michael ULiege

Conference (2016, July)

Detailed reference viewed: 28 (7 ULiège)
See detailAccounting for price endogeneity in airline itinerary choice models
Lurkin, Virginie ULiege; Garrow, Laurie; Higgins, Matthew et al

Conference (2016, May 20)

This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables ... [more ▼]

This study formulates an itinerary choice model that is consistent with those used by industry and corrects for price endogeneity using a control function that uses several types of instrumental variables. We estimate our models using database of more than 3 million tickets provided by the Airlines Reporting Corporation. Results based on Continental U.S. markets for May 2013 departures show that models that fail to account for price endogeneity overestimate customers’ value of time and result in biased price estimates and incorrect pricing recommendations. Extensions to advanced discrete choice models show the importance of accounting for inter-alternative substitution for products that share similar departure times. [less ▲]

Detailed reference viewed: 56 (6 ULiège)
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See detailEarly Detection of University Students in Potential Difficulty
Hoffait, Anne-Sophie ULiege; Schyns, Michael ULiege

E-print/Working paper (2016)

Using data mining methods, this paper presents a new means of identifying freshmen's profiles likely to face major difficulties to complete their first academic year. Academic failure is a relevant issue ... [more ▼]

Using data mining methods, this paper presents a new means of identifying freshmen's profiles likely to face major difficulties to complete their first academic year. Academic failure is a relevant issue at a time when post-secondary education is ever more critical to economic success. We aim at early detection of potential failure using student data available at registration, i.e. school records and environmental factors, with a view to timely and efficient remediation and/or study reorientation. For the sake of accuracy, we adapt three data mining methods, namely random forest, logistic regression and artificial neural network algorithms. Real data pertaining to undergraduates at the University of Liège (Belgium), illustrates our methodology. [less ▲]

Detailed reference viewed: 41 (20 ULiège)
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See detailA Comparison of Departure Time of Day Formulations
Lurkin, Virginie ULiege; Garrow, Laurie; Higgins, Matthew et al

E-print/Working paper (2016)

Airline passengers’ itinerary choices are influenced by many factors including carriers, prices, the number of connections, and departure times. This paper compares three different methods that have been ... [more ▼]

Airline passengers’ itinerary choices are influenced by many factors including carriers, prices, the number of connections, and departure times. This paper compares three different methods that have been used to model departure time of day preferences. The first is a discrete formulation that uses indicator variables to represent the hour of departure. The next two methods are based on a continuous formulation that uses a series of sine and cosine functions. One assumes departure time preferences over a 24-hour cycle and the other uses shorter cycle lengths that account for fewer departures during certain hours of the day. We compare models using itineraries in the Continental U.S. that are separated by two time zones. Although the discrete formulation fits the data better, the two continuous time of day formulations are preferred as they provide more intuitive predictions and require fewer parameters. Results between the two continuous time of day formulations are similar but differ in how strongly they weight itineraries that depart very early or very late in the day. Based on empirical results, we recommend testing both 24-hour and less than 24-hour cycle lengths for a particular dataset. [less ▲]

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See detailContinuous Departure Time of Day Preferences for Continental U.S. Airline Markets Segmented by Distance, Direction of Travel, Number of Time Zones, Day of Week and Itinerary Type
Lurkin, Virginie ULiege; Garrow, Laurie; Higgins, Matthew et al

E-print/Working paper (2016)

Airlines use itinerary choice models to allocate the total number of passengers in a city pair to specific itineraries. In a related paper, we estimated a multinomial logit (MNL) itinerary choice model ... [more ▼]

Airlines use itinerary choice models to allocate the total number of passengers in a city pair to specific itineraries. In a related paper, we estimated a multinomial logit (MNL) itinerary choice model using database of more than 3 million tickets for Continental U.S. markets provided by the Airlines Reporting Corporation that accounted for price endogeneity. The size and comprehensiveness of our database allowed us to estimate highly refined continuous departure time of day preference curves that account for distance, direction of travel, the number of time zones traversed, departure day of week and itinerary type (outbound, inbound or one-way). This paper and accompanying Excel spreadsheet located at http://garrowlab.ce.gatech.edu contain the results of all model coefficients (including the 1260 time of day parameters) and summarize results in a series of ten figures. These highly-refined time of day preference curves can be used by airlines, researchers, and government organizations in the evaluation of demand-management and other policies. [less ▲]

Detailed reference viewed: 80 (6 ULiège)