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Centralized vs. decentralized ambulance diversion / Sarang Deo in Management science, Vol. 57 N° 7 (Juillet 2011) 

Public ISBD [article]  in Management science > Vol. 57 N° 7 (Juillet 2011) . - pp. 1300-1319 Titre : Centralized vs. decentralized ambulance diversion : A network perspective Type de document : texte imprimé Auteurs : Sarang Deo, Auteur ; Gurvich Itai, Auteur Année de publication : 2011 Article en page(s) : pp. 1300-1319 Note générale : Management Langues : Anglais (eng) Mots-clés : Emergency  department  Ambulance  diversion  Game  theory  Queueing  networks Index. décimale : 658 Organisation des entreprises. Techniques du commerce Résumé : One of the most important operational challenges faced by emergency departments (EDs) in the United States is patient overcrowding. In periods of overcrowding, an ED can request the emergency medical services (EMS) agency to divert incoming ambulances to neighboring hospitals, a phenomenon known as “ambulance diversion.” The EMS agency may accept this request provided that at least one of the neighboring EDs is not on diversion. From an operations perspective, properly executed ambulance diversion should result in resource pooling and reduce the overcrowding and delays in a network of EDs. Recent evidence indicates, however, that this potential benefit is not always realized. In this paper, we provide one potential explanation for this discrepancy and suggest potential remedies. Using a queueing game between two EDs that aim to minimize their own waiting time, we find that decentralized decisions regarding diversion explain the lack of pooling benefits. Specifically, we find the existence of a defensive equilibrium, wherein each ED does not accept diverted ambulances from the other ED. This defensiveness results in a depooling of the network and, subsequently, in delays that are significantly higher than when a social planner coordinates diversion. The social optimum is itself difficult to characterize analytically and has limited practical appeal because it depends on problem parameters such as arrival rates and length of stay. Instead, we identify an alternative solution that does not require the exact knowledge of the parameters and may be used by the EMS agencies to coordinate diversion decisions when defensive diversion is present. We show that this solution is approximately optimal for the social planner's problem. Moreover, it is Pareto improving over the defensive equilibrium whereas the social optimum, in general, might not be. DEWEY : 658 ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/57/7.toc [article] Centralized vs. decentralized ambulance diversion : A network perspective [texte imprimé] / Sarang Deo, Auteur ; Gurvich Itai, Auteur . - 2011 . - pp. 1300-1319. Management Langues : Anglais (eng) in Management science > Vol. 57 N° 7 (Juillet 2011) . - pp. 1300-1319 Mots-clés : Emergency  department  Ambulance  diversion  Game  theory  Queueing  networks Index. décimale : 658 Organisation des entreprises. Techniques du commerce Résumé : One of the most important operational challenges faced by emergency departments (EDs) in the United States is patient overcrowding. In periods of overcrowding, an ED can request the emergency medical services (EMS) agency to divert incoming ambulances to neighboring hospitals, a phenomenon known as “ambulance diversion.” The EMS agency may accept this request provided that at least one of the neighboring EDs is not on diversion. From an operations perspective, properly executed ambulance diversion should result in resource pooling and reduce the overcrowding and delays in a network of EDs. Recent evidence indicates, however, that this potential benefit is not always realized. In this paper, we provide one potential explanation for this discrepancy and suggest potential remedies. Using a queueing game between two EDs that aim to minimize their own waiting time, we find that decentralized decisions regarding diversion explain the lack of pooling benefits. Specifically, we find the existence of a defensive equilibrium, wherein each ED does not accept diverted ambulances from the other ED. This defensiveness results in a depooling of the network and, subsequently, in delays that are significantly higher than when a social planner coordinates diversion. The social optimum is itself difficult to characterize analytically and has limited practical appeal because it depends on problem parameters such as arrival rates and length of stay. Instead, we identify an alternative solution that does not require the exact knowledge of the parameters and may be used by the EMS agencies to coordinate diversion decisions when defensive diversion is present. We show that this solution is approximately optimal for the social planner's problem. Moreover, it is Pareto improving over the defensive equilibrium whereas the social optimum, in general, might not be. DEWEY : 658 ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/57/7.toc

Consumption externality and yield uncertainty in the influenza vaccine supply chain / Kenan Arifoglu in Management science, Vol. 58 N° 6 (Juin 2012) 

Public ISBD [article]  in Management science > Vol. 58 N° 6 (Juin 2012) . - pp.1072-1091 Titre : Consumption externality and yield uncertainty in the influenza vaccine supply chain : Interventions in demand and supply sides Type de document : texte imprimé Auteurs : Kenan Arifoglu, Auteur ; Sarang Deo, Auteur ; Seyed M. R. Iravani, Auteur Année de publication : 2012 Article en page(s) : pp.1072-1091 Note générale : Management Langues : Anglais (eng) Mots-clés : Influenza  vaccine  Supply  chain  inefficiency  Strategic  consumer  behavior  Externality  Yield  uncertainty Résumé : We study the impact of yield uncertainty (supply side) and self-interested consumers (demand side) on the inefficiency in the influenza vaccine supply chain. Previous economic studies, focusing on demand side, find that the equilibrium demand is always less than the socially optimal demand because self-interested individuals do not internalize the social benefit of protecting others via reduced infectiousness (positive externality). In contrast, we show that the equilibrium demand can be greater than the socially optimal demand after accounting for the limited supply due to yield uncertainty and manufacturer's incentives. The main driver for this result is a second (negative) externality: Self-interested individuals ignore that vaccinating people with high infection costs is more beneficial for the society when supply is limited. We show that the extent of the negative externality can be reduced through more efficient and less uncertain allocation mechanisms. To investigate the relative effectiveness of government interventions on supply and demand sides under various demand and supply characteristics, we construct two partially centralized scenarios where the social planner (i.e., government) intervenes either on the demand side or the supply side, but not both. We conduct an extensive numerical analysis. ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/58/6/1072.short [article] Consumption externality and yield uncertainty in the influenza vaccine supply chain : Interventions in demand and supply sides [texte imprimé] / Kenan Arifoglu, Auteur ; Sarang Deo, Auteur ; Seyed M. R. Iravani, Auteur . - 2012 . - pp.1072-1091. Management Langues : Anglais (eng) in Management science > Vol. 58 N° 6 (Juin 2012) . - pp.1072-1091 Mots-clés : Influenza  vaccine  Supply  chain  inefficiency  Strategic  consumer  behavior  Externality  Yield  uncertainty Résumé : We study the impact of yield uncertainty (supply side) and self-interested consumers (demand side) on the inefficiency in the influenza vaccine supply chain. Previous economic studies, focusing on demand side, find that the equilibrium demand is always less than the socially optimal demand because self-interested individuals do not internalize the social benefit of protecting others via reduced infectiousness (positive externality). In contrast, we show that the equilibrium demand can be greater than the socially optimal demand after accounting for the limited supply due to yield uncertainty and manufacturer's incentives. The main driver for this result is a second (negative) externality: Self-interested individuals ignore that vaccinating people with high infection costs is more beneficial for the society when supply is limited. We show that the extent of the negative externality can be reduced through more efficient and less uncertain allocation mechanisms. To investigate the relative effectiveness of government interventions on supply and demand sides under various demand and supply characteristics, we construct two partially centralized scenarios where the social planner (i.e., government) intervenes either on the demand side or the supply side, but not both. We conduct an extensive numerical analysis. ISSN : 0025-1909 En ligne : http://mansci.journal.informs.org/content/58/6/1072.short