Cumulative dominance and heuristic performance in binary multi-attribute choice

Working paper 895, Department of Economics and Business, Universitat Pompeu FabraSeveral studies have reported high performance of simple decision heuristics in multi-attribute decision making. In this paper, we focus on situations where attributes are binary and analyze the performance of Deterministic-Elimination-By-Aspects (DEBA) and similar decision heuristics. We consider non-increasing weights and two probabilistic models for the attribute values: one where attribute values are independent Bernoulli randomvariables; the other one where they are binary random variables with inter-attribute positive correlations. Using these models, we show that good performance of DEBA is explained by the presence of cumulative as opposed to simple dominance. We therefore introduce the concepts of cumulative dominance compliance and fully cumulative dominance compliance and show that DEBA satisfies those properties. We derive a lower bound with which cumulative dominance compliant heuristics will choose a best alternative and show that, even with many attributes, this is not small. We also derive an upper bound for the expected loss of fully cumulative compliance heuristics and show that this is moderate even when the number of attributes is large. Both bounds are independent of the values of the weights.Postprint (author’s final draft

Cumulative dominance and heuristic performance in binary multi-attribute choice

Several studies have reported high performance of simple decision heuristics multi-attribute decision making. In this paper, we focus on situations where attributes are binary and analyze the performance of Deterministic-Elimination-By-Aspects (DEBA) and similar decision heuristics. We consider non-increasing weights and two probabilistic models for the attribute values: one where attribute values are independent Bernoulli randomvariables; the other one where they are binary random variables with inter-attribute positive correlations. Using these models, we show that good performance of DEBA is explained by the presence of cumulative as opposed to simple dominance. We therefore introduce the concepts of cumulative dominance compliance and fully cumulative dominance compliance and show that DEBA satisfies those properties. We derive a lower bound with which cumulative dominance compliant heuristics will choose a best alternative and show that, even with many attributes, this is not small. We also derive an upper bound for the expected loss of fully cumulative compliance heuristics and show that this is moderate even when the number of attributes is large. Both bounds are independent of the values of the weights.Multi-attribute decision making, binary attributes, DEBA, cumulative dominance, performance bounds, Leex

Effects of forest fragmentation on the vertical stratification of neotropical bats

Vertical stratification is a key component of the biological complexity of rainforests. Understanding community- and species-level responses to disturbance across forest strata is paramount for evidence-based conservation and management. However, even for bats, known to extensively explore multiple layers of the complex three-dimensional forest space, studies are biased towards understory-based surveys and only few assessments of vertical stratification were done in fragmented landscapes. Using both ground and canopy mist-nets, we investigated how the vertical structure of bat assemblages is influenced by forest fragmentation in the experimentally fragmented landscape of the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. Over a three year-period, we captured 3077 individuals of 46 species in continuous forest (CF) and in 1, 10 and 100 ha forest fragments. In both CF and forest fragments, the upper forest strata sustained more diverse bat assemblages than the equivalent understory layer, and the midstory layers had significantly higher bat abundance in fragments than in CF. Artibeus lituratus and Rhinophylla pumilio exhibited significant shifts in their vertical stratification patterns between CF and fragments (e.g. R. pumilio was more associated with the upper strata in fragments than in CF). Altogether, our study suggests that fragmentation modulates the vertical stratification of bat assemblages

Tight upper bounds for the expected loss of lexicographic heuristics in binary multiattribute choice

Tight upper bounds for the expected loss of the DEBA (Deterministic-Elimination-By-Aspects) lexicographic selection heuristic are obtained for the case of an additive separable utility function with unknown non-negative, non-increasing attribute weights for numbers of alternatives and attributes as large as 10 under two probabilistic models: one in which attributes are assumed to be independent Bernouilli random variables and another one with positive inter-attribute correlation. The upper bounds improve substantially previous bounds and extend significantly the cases in which a good performance of DEBA can be guaranteed under the assumed cognitive limitations.Postprint (published version

Assessment of cochlear toxicity in response to chronic 3,3'-iminodipropionitrile in mice reveals early and reversible functional loss that precedes overt histopathology

The peripheral auditory and vestibular systems rely on sensorineural structures that are vulnerable to ototoxic agents that cause hearing loss and/or equilibrium deficits. Although attention has focused on hair cell loss as the primary pathology underlying ototoxicity, evidence from the peripheral vestibular system indicates that hair cell loss during chronic exposure is preceded by synaptic uncoupling from the neurons and is potentially reversible. To determine if synaptic pathology also occurs in the peripheral auditory system, we examined the extent, time course, and reversibility of functional and morphological alterations in cochleae from mice exposed to 3,3′-iminodipropionitrile (IDPN) in drinking water for 2, 4 or 6 weeks. Functionally, IDPN exposure caused progressive high- to low-frequency hearing loss assessed by measurement of auditory brainstem response wave I absolute thresholds and amplitudes. The extent of hearing loss scaled with the magnitude of vestibular dysfunction assessed behaviorally. Morphologically, IDPN exposure caused progressive loss of outer hair cells (OHCs) and synapses between the inner hair cells (IHCs) and primary auditory neurons. In contrast, IHCs were spared from ototoxic damage. Importantly, hearing loss consistent with cochlear synaptopathy preceded loss of OHCs and synapses and, moreover, recovered if IDPN exposure was stopped before morphological pathology occurred. Our observations suggest that synaptic uncoupling, perhaps as an early phase of cochlear synaptopathy, also occurs in the peripheral auditory system in response to IDPN exposure. These findings identify novel mechanisms that contribute to the earliest stages of hearing loss in response to ototoxic agents and possibly other forms of acquired hearing loss

Efecto de la inclusión de distintas fuentes de grasa en dietas para pollos broiler sobre el perfil lipídico de la carne, la grasa abdominal y la piel

Se realizó una prueba experimental con 600 pollos broiler de la estirpe comercial Arbor-Acres, alimentándoles con dietas suplementadas con un 8% de sebo (S) , aceite de palma (AP) y oleina de soja-girasol (OSG). Al final del periodo productivo, los animales, con 49 días de vida, fueron sacrificados en un matadero comercial, seleccionándose las canales de los 10 animales, de cada tratamiento, con el peso vivo más próximo al valor medio del correspondiente tratamiento, para su posterior dissección y toma de pechugas, muslos, y muestras de grasa abdominal y piel. Todas las muestras se conservaron a -20°C hasta la realización de los correspondientes análisis cromatográficos. Los animales que habían consumido la dieta suplementada con OSG mostraron, en los tejidos analizados, los niveles más altos de ácido linoleico (C18:2) así como un mayor grado de insaturación. Los tejidos de los animales alimentados con AP y S contenían mayores proporciones de ácido palmítico (C16:0) y ácido oleico (C18:l), respectivamente

Increase of geometrical and positional fatty acid isomers in dark meat from broilers fed heated oils

Oxidation of polyunsaturated fatty acids leads to primary and secondary oxidation products. Compounds and amounts of these products vary, depending on the oxidative conditions. As these oxidation products have different absorption and biological effects, we performed two different heating treatments on sunflower oil. The first was heating the oil at 190-195"C for 28 h i.e. very oxidised oil); and the other, heating at 60"C for 12 days (i.e. pcroxidiscd oil). In the frame of this study, we compared the fatty acid composition of a refined sunflower oil (fresh oil), the pcroxidiscd oil, the very oxidised oil, and a mixture (1+1) of fresh and very oxidised oil (i.e. oxidised oil). Oil fatty acid compositions were affected by the heating treatments. In to addition, different fatty acid isomers were formed during heating at 190-I95°C and significant differences were found between thcir.contcnt in the sunflower oils. We also studied the effect of feeding broilers with these oils and Zn and tocopherol supplements on the fatty acid composition of their raw dark meat. Various Irons fatty acid isomers increased in dark meat from broilers fed oxidised and very oxidised oils. In addition, discriminant analysis showed that ditrans-CLA content was able to distinguish dark chicken meat from chickens fed sunflower oils heated at 190-195"C

Comparative digestibility and productive performances between Landrace and Iberian pigs fed on a corn- or a sorghum-acorn- based diet

Although digestible energy (DE) values for most commonly used feeds in pig industry are mainly predicted by their chemical composition, other likely effects could affect digestibility. The present paper try to explore the effects likely caused by animal breed (lean v. fat line) and dietary ingredients used