An Alternative Theoretical Explanation and Empirical Insights into Overordering Behavior in Supply Chains*

The beer game and the supply line underweighting theory are central to our knowledge of decision making in dynamic environments such as supply chains. The core of these theories is that people are incapable of recognizing the pipeline inventory and this is the main cause of overordering and dysfunctional behavior. This article identifies lacunae in the theoretical and empirical foundations of extant literature and proposes an alternate explanation, a “correction model,” explaining why overreactions occur. We adopt a multi‐method research design, comprising a field case study and laboratory experiments, to ground our findings. [Submitted: July 19, 2010. Revisions received: December 8, 2010; March 14, 2011. Accepted: March 28, 2011.]     

Ein Optimierungsmodell für die wöchentliche Tourenplanung unter Einbeziehung der EU-Sozialvorschriften

The Regulation (EC) No 561/2006 and the Directive 2002/15/EC concern the driving and working hours as well as breaks and rest periods of drivers in road transportation. Although the regulations have an enormous effect on vehicle routing and scheduling, only parts of them have been integrated in few solution approaches and some vehicle routing models so far. This paper starts with the presentation of the restrictions of the relevant European Community regulations. Then, a mixed integer linear programming model for the vehicle routing problem with time windows including all rules of the regulations for a planning horizon of an entire week is presented. The model is solved with CPLEX and the impact of the regulations on the resulting vehicle schedules is analyzed by means of computational experiments.     

Corporate social responsibility: a strategic and profitable response to entry?

This paper investigates whether an incumbent has an incentive to introduce corporate social responsibility (CSR) activities only as a response to entry by a competitor, i.e., the incumbent would eschew CSR if left uncontested. We assume that the entrant cannot provide CSR at least at the outset for two reasons: (1) it would not be credible due to its lack of recognition and (2) due to high fixed cost to pay e.g., for licensing. More precisely, this paper shows that monopolistic firms can have indeed the incentive to introduce CSR activities only as a response to entry. Therefore, increased competition can turn a firm “green”, providing a “win–win” for business as well as for the environment.     

Determining the non-inferiority margin for patient reported outcomes

One of the cornerstones of any non-inferiority trial is the choice of the non-inferiority margin delta. This threshold of clinical relevance is very difficult to determine, and in practice, delta is often "negotiated" between the sponsor of the trial and the regulatory agencies. However, for patient reported, or more precisely patient observed outcomes, the patients' minimal clinically important difference (MCID) can be determined empirically by relating the treatment effect, for example, a change on a 100-mm visual analogue scale, to the patient's satisfaction with the change. This MCID can then be used to define delta. We used an anchor-based approach with non-parametric discriminant analysis and ROC analysis and a distribution-based approach with Norman's half standard deviation rule to determine delta in three examples endometriosis-related pelvic pain measured on a 100-mm visual analogue scale, facial acne measured by lesion counts, and hot flush counts. For each of these examples, all three methods yielded quite similar results. In two of the cases, the empirically derived MCIDs were smaller or similar of deltas used before in non-inferiority trials, and in the third case, the empirically derived MCID was used to derive a responder definition that was accepted by the FDA. In conclusion, for patient-observed endpoints, the delta can be derived empirically. In our view, this is a better approach than that of asking the clinician for a "nice round number" for delta, such as 10, 50%, π, e, or i.