Egbert van der Veen

ORchestra: an online reference database of OR/MS literature in health care

We introduce the categorized reference database ORchestra, which is available online at http://www.utwente.nl/choir/orchestra/.

A case study of cost-efficient staffing under annualized hours

We propose a mathematical programming formulation that incorporates annualized hours and shows to be very flexible with regard to modeling various contract types. The objective of our model is to minimize salary cost, thereby covering workforce demand, and using annualized hours. Our model is able to address various business questions regarding tactical workforce planning problems, e.g., with regard to annualized hours, subcontracting, and vacation planning. In a case study for a Dutch hospital two of these business questions are addressed, and we demonstrate that applying annualized hours potentially saves up to 5.2% in personnel wages annually.

Shift rostering using decomposition: assign weekend shifts first

This paper introduces a shift rostering problem that surprisingly has not been studied in the literature: the weekend shift rostering problem. It is motivated by our experience that employees’ shift preferences predominantly focus on the weekends, since many social activities happen during weekends. The weekend rostering problem (WRP) addresses the rostering of weekend shifts, for which we design a problem-specific heuristic. We consider the WRP as the first phase of the shift rostering problem. To complete the shift roster, the second phase assigns the weekday shifts. This decomposition reflects how shift rosters are often created manually in practice, which makes the decomposition method proposed in this paper a more intuitive approach for business users compared to approaches without this decomposition. We believe that such approaches enable business users to effectively analyze and steer the outcomes of algorithms for shift rostering especially on criteria that are relevant to them such as those concerning weekends. We analyze and discuss effects of this two-phase approach both on the weekend shift roster and on the roster as a whole. We demonstrate that our first-phase weekend rostering heuristic is effective both on generated instances and real-life instances. For situations where the weekend shift roster is one of the key determinants of the quality of the complete roster, our two-phase approach is shown to be effective.

An assessment of a days off decomposition approach to personnel shift scheduling

This paper studies a two-phase decomposition approach to solving the personnel scheduling problem. The first phase creates a days-off-schedule, indicating working days and days off for each employee. The second phase assigns shifts to the working days in the days-off-schedule. This decomposition is motivated by the fact that personnel scheduling constraints are often divided into two categories: one specifies constraints on working days and days off, while the other specifies constraints on shift assignments. To assess the consequences of the decomposition approach, we apply it to public benchmark instances, and compare this to solving the personnel scheduling problem directly. In all steps we use mathematical programming. We also study the extension that includes night shifts in the first phase of the decomposition. We present a detailed results analysis, and analyze the effect of various instance parameters on the decompositions’ results. In general, we observe that the decompositions significantly reduce the computation time, but the quality, though often good, depends strongly on the instance at hand. Our analysis identifies which aspects in the instance can jeopardize the quality.

Jaarurenplanningen: schakel tussen formatiebegroting en dienstroostering

Jaarurenplanningen vormen een methodiek om het gat tussen de begroting van personeelsbudgetten en formatiesamenstelling en de operationele inzetplanning van personeel te dichten. Jaarurenplanningen beschrijven een planning op het niveau van weken tot maanden, waarin de inzet van personeel (in uren per week/maand) wordt afgestemd op een ingeschat productieniveau (een verwachte vraag naar zorg). Daarmee wordt voorkomen dat er momenten (weken) van onderbezetting zijn en, tegelijkertijd, momenten (andere weken) van overbezetting. Een aan twee kanten snijdend mes als het gaat om beheersing van kosten, maar ook als het gaat om kwaliteit van dienstverlening. Het laatste doordat er meer momenten zijn van een goed op de vraag naar zorg afgestemd aanbod aan zorgcapaciteit. Aan de hand van een aantal voorbeelden motiveren wij het nut van jaarurenplanningen en we presenteren, zonder op wiskundige details in te gaan, een rekenmodel om jaarurenplanningen te ondersteunen.