Contrasts between utility maximisation and regret minimisation in the presence of opt out alternatives

An increasing number of studies of choice behaviour are looking at Random Regret Minimisation (RRM) as an alternative to the well established Random Utility Maximisation (RUM) framework. Empirical evidence tends to show small differences in performance between the two approaches, with the implied preference between the models being dataset specific. In the present paper, we discuss how in the context of choice tasks involving an opt out alternative, the differences are potentially more clear cut. Specifically, we hypothesise that when opt out alternatives are framed as a rejection of all the available alternatives, this is likely to have a detrimental impact on the performance of RRM, while the performance of RUM suffers more than RRM when the opt out is framed as a respondent being indifferent between the alternatives on offer. We provide empirical support for these hypotheses through two case studies, using the two different types of opt out alternatives. Our findings suggest that analysts need to carefully evaluate their choice of model structure in the presence of opt out alternatives, while any a priori preference for a given model structure should be taken into account in survey framing

Revealing consumer preferences by observing information search

Motivated by the notion that consumers' use of the internet creates a wealth of data on information search, we put forward the idea that observed information searches may be used for deriving consumer preferences. First, we derive a theoretical model of consumer behaviour under uncertainty and information availability. In theory, this model provides the opportunity to derive consumer preferences from information search alone. The model is then illustrated, based on an articial dataset. Estimation results show that information search concerning an uncertain attribute of a good can indeed be used to identify consumer preferences concerning the good. Although the proposed model relies on a number of assumptions (for example the premises behind expected utility maximisation) we show how these can be relaxed without compromising the potential of the approach in general

Determining the probability of cyanobacterial blooms: the application of Bayesian networks in multiple lake systems

A Bayesian network model was developed to assess the combined influence of nutrient conditions and climate on the occurrence of cyanobacterial blooms within lakes of diverse hydrology and nutrient supply. Physicochemical, biological, and meteorological observations were collated from 20 lakes located at different latitudes and characterized by a range of sizes and trophic states. Using these data, we built a Bayesian network to (1) analyze the sensitivity of cyanobacterial bloom development to different environmental factors and (2) determine the probability that cyanobacterial blooms would occur. Blooms were classified in three categories of hazard (low, moderate, and high) based on cell abundances. The most important factors determining cyanobacterial bloom occurrence were water temperature, nutrient availability, and the ratio of mixing depth to euphotic depth. The probability of cyanobacterial blooms was evaluated under different combinations of total phosphorus and water temperature. The Bayesian network was then applied to quantify the probability of blooms under a future climate warming scenario. The probability of the "high hazardous" category of cyanobacterial blooms increased 5% in response to either an increase in water temperature of 0.8°C (initial water temperature above 24°C) or an increase in total phosphorus from 0.01 mg/L to 0.02 mg/L. Mesotrophic lakes were particularly vulnerable to warming. Reducing nutrient concentrations counteracts the increased cyanobacterial risk associated with higher temperatures

Zwammerdam on the Rhine: the contribution of archaeozoological research to the current knowledge of Roman Nigrum Pullum

The Dutch Roman frontier is known for providing a great deal of archaeozoological research, but the real potential has not been reached yet as there are data from many excavated sites that have still not been analysed in detail or are ́buried́ as grey literature. The research project Romeinse vicus aan de Rijn aims at filling this gap through the study and publication of Roman military vici along the Dutch part of the Rhine to better understand the development and significance of these key locations. Within this frame, archaeozoological remains from various sites are being re-analysed in order to reinforce the knowledge of economic and cultural patterns, to better understand supply networks and to study how these activities shaped the surrounding environment and impacted the landscape.One of the studied sites is the Roman fort and vicus of Zwammerdam-Nigrum Pullum, located on the Rhine in the West Netherlands. Archaeozoological remains were collected during excavations in 1968–1971 and in 2003–2004, but some of the material was not studied, and a thorough synthesis was still missing. Because of this, certain aspects within this Roman settlement remain poorly analysed.With a thorough analysis of the archaeozoological remains from both excavations at Zwammerdam, integrated with contextual and chronological data, this study brings forward new archaeozoological information for this Roman settlement. The new data not only make it possible to compare animal exploitation in the vicus with that of the fort, but it also provides an opportunity to analyse these patterns throughout time both locally and regionally. While limited to a small area in the Roman Empire, the data from Zwammerdam can provide a further step for new, broader archaeozoological research towards the role of animals in the Roman culture and economy.Bioarchaeolog

Modeling power corrections to the Bjorken sum rule for the neutrino structure function F_1

Direct measurements of the the structure functions F_1^{nu p} and F_1^{nu n} at a neutrino factory would allow for an accurate extraction of alpha_s from the Q^2-dependence of the Bjorken sum rule, complementing that based on the Gross-Llewellyn-Smith sum rule for F_3. We estimate the power (1/Q^2-) corrections to the Bjorken sum rule in the instanton vacuum model. For the reduced matrix element of the flavor-nonsinglet twist-4 operator ubar_g_Gdual_gamma_gamma5_u - (u -> d) we obtain a value of 0.18 GeV^2, in good agreement with the QCD sum rule calculations of Braun and Kolesnichenko. Our result allows to reduce the theoretical error in the determination of alpha_s.Comment: 3 pages, 1 figure, uses iopart.cls. Proceedings of the 4th NuFact'02 Workshop "Neutrino Factories based on Muon Storage Rings", Imperial College, London, July 1-6, 200