Optimal choice of electoral preference data

Electoral researchers are so much accustomed to analyzing the choice of the single most preferred party as the left-hand side variable of their models of electoral behavior that they often ignore revealed preference data. Drawing on random utility theory, their models predict electoral behavior at the extensive margin of choice. Since the seminal work of Luce and others on individual choice behavior, however, many social science disciplines (consumer research, labor market research, travel demand, etc.) have extended their inventory of observed preference data with, for instance, multiple paired comparisons, complete or incomplete rankings, and multiple ratings. Eliciting (voter) preferences using these procedures and applying appropriate choice models is known to considerably increase the efficiency of estimates of causal factors in models of (electoral) behavior. In this paper, we demonstrate the efficiency gain when adding additional preference information to first preferences, up to full ranking data. We do so for multi-party systems of different sizes. We use simulation studies as well as empirical data from the 1972 German election study. Comparing the practical considerations for using ranking and single preference data results in suggestions for choice of measurement instruments in different multi-candidate and multi-party settings.

Are the preference and selection patterns of hermit crabs for gastropod shells species- or site-specific?

Experimental analyses of hermit crabs and their preferences for shells are essential to understand the intrinsic relationship of the crabs' dependence on shells, and may be useful to explain their shell use pattern in nature. The aim of this study was to evaluate the effect of crab species and site on the pattern of shell use, selection, and preference in the south-western Atlantic hermit crabs Pagurus brevidactylus and Pagurus criniticornis, comparing sympatric and allopatric populations. Differently from the traditional approach to evaluate shell preference by simply determining the shell selection pattern (i.e., the number of shells of each type selected), preference was defined (according to [Liszka, D., Underwood, AJ., 1990. An experimental design to determine preferences for gastropod shells by a hermit-crab. J. Exp. Mar. Biol. Ecol., 137(1), 47-62]) by the comparison of the number of crabs changing for a particular shell type when three options were given (Cerithium atratum, Morula nodulosa, and Tegula viridula) with the number of crabs changing for this same type when only this type was offered. The effect of crab species was tested at Cabelo Gordo Beach, where P. brevidacrylus was found occupying shells of C. atratum, M. nodulosa, and T viridula in similar frequencies, whereas P. criniticornis occupied predominantly shells of C atratum. In laboratory experiments the selection patterns of the two hermit-crab species for these three gastropods were different, with P criniticornis selecting mainly shells of C atratum, and R brevidactylus selecting more shells of M. nodulosa. The shell preference was also dependent on crab species, with P. criniticornis showing a clear preference for shells of C atratum, whereas P. brevidactylus did not show a preference for any of the tested shells. The effect of site was tested for the two species comparing data from Cabelo Gordo to Preta (P brevidactylus) and Araca beaches (P. criniticornis). The pattern of shell use, selection, and preference was demonstrated to be dependent on site only for P. brevidactylus. The results also showed that the shell use pattern of P criniticornis can be explained by its preference at both sites, whereas for P. brevidactylus it occurred only at Cabelo Gordo, where the absence of preference was correlated with the similar use of the three gastropod species studied. Finally, the results showed that the shell selection pattern cannot be considered as a measure of shell preference, since it overestimates crab selectivity. (C) 2009 Elsevier B.V. All rights reserved.

Red wine sweetness preference according to consumer segmentation

The present work aims to evaluate the acceptance and preference for sweet taste in red wine, according to consumer segmentation in age, gender, personality type, tasting sensitivity and consumer experience in wine. A hundred and fourteen wine tasters were invited to the wine tasting, and the average age was 27 years. An addition of sugar was made with equal concentrations of glucose and fructose to the wine at 2g/L, 4g/L, 8g/L, 16g/L and 32g/L. Five pairs of glasses were presented for the subjects to taste containing each a control wine and a spiked sample. Pairs were presented in order of concentration, from 2g/L to 32g/l. The subjects were also asked to answer two online questionnaires at the end of the tasting, on the personality types and vinotype, which is related to mouth sensitivity. ISO-5495 paired comparison tests were used for sensorial analysis. The objective was to assess if any of the nine segmentation factors had influence on preference or rejection for spiked samples and to establish whether this preference was statistically significant. We concluded that it would be important to have subjects with an age average higher than 27 years and more experienced in wine drinking, mostly because the data relative to preferences in novices shows some dispersion and lack of attention. A panel of older and more experienced wine tasters is likely to be more attentive and focused and therefore yield differentiated results. It was also concluded that more research is required to extend this investigation to other wine styles because the differences in preferences can depend on other reasons, such as preferring a wine with more or less sugar according to the type of wine. Finally it was concluded also that some variables influence preference for sweet taste in red wine, such as gender, vinotype and category of experience

The compleat gamester : or, Full and easy instructions for playing at above twenty several games upon the cards with variety of diverting fancies and tricks upon the same now first added ; as likewise at all the games on the tables, together with the royal game of chess and billiards.

Mode of access: Internet.

Effects of salt and fat combinations on taste preference and perception

Fat and salt are a common and attractive combination in food and overconsumption of either is associated with negative health outcomes. The major aim was to investigate contributions and interactions of salt and fat on taste pleasantness and perception. The minor aim was to investigate individual fat taste sensitivity (detection threshold of oleic acid [C18:1]) on pleasantness for fat. In a complete factorial design, 49 participants (18-54 years, 12 males) tasted tomato soups with 4 different fat concentrations (0-20%) and 5 different salt concentrations (0.04-2.0%). The preferred concentration and the discrimination ability for both fat and salt were determined by ranking tests. Results show that salt and fat affected pleasantness separately (P < 0.01), with salt having the strongest effect. Fat concentrations 0%, 5%, and 10% did not differ in pleasantness, whereas 20% was less pleasant (P < 0.05). There were no interactions for fat and salt on pleasantness or saltiness and fattiness intensity. Fat taste sensitive participants preferred lower fat concentrations than less sensitive participants (P = 0.008). In conclusion, the strong effect of salt on pleasantness in this study suggests that salt, rather than fat, play a major role in the attraction to savory fatty foods.

An empirical study of user perceived usefulness and preference of open learner model visualisations

Many higher education institutions have reformed their academic programmes to adopt unit learning outcomes. It is essential for effective learning management tools to support this fundamental transformation. We see the need for a tool that provides visualisations of Open Learner Models (OLM) and associated e-portfolio content to guide students in achieving intended learning outcomes, help evidence their learning andkeep them engaged in their study. OLMs surface the relationship between learning activities and tasks, formative and summativeassessment, and intended learning outcomes. We have developedand validated a set of candidate visualisations for such OLMs. We report key findings from our study in terms of potential users’ feedback on our tool’s support for tracking learning progress against learning outcomes. Our findings can inform and refine learning management systems.

Preference inference based on Pareto models

In this paper, we consider Preference Inference based on a generalised form of Pareto order. Preference Inference aims at reasoning over an incomplete specification of user preferences. We focus on two problems. The Preference Deduction Problem (PDP) asks if another preference statement can be deduced (with certainty) from a set of given preference statements. The Preference Consistency Problem (PCP) asks if a set of given preference statements is consistent, i.e., the statements are not contradicting each other. Here, preference statements are direct comparisons between alternatives (strict and non-strict). It is assumed that a set of evaluation functions is known by which all alternatives can be rated. We consider Pareto models which induce order relations on the set of alternatives in a Pareto manner, i.e., one alternative is preferred to another only if it is preferred on every component of the model. We describe characterisations for deduction and consistency based on an analysis of the set of evaluation functions, and present algorithmic solutions and complexity results for PDP and PCP, based on Pareto models in general and for a special case. Furthermore, a comparison shows that the inference based on Pareto models is less cautious than some other types of well-known preference model.

Article 27(3)(b) TRIPS and plant variety protection in developing countries

In comparison with industrialised countries, agriculture in developing countries accounts for a substantial share of GDP and involves a substantial sector of small-holders and traditional agriculturalists. In view of these differences, the biotechnology clause of Article 27.3.b TRIPS with its requirement of plant variety protection either by patents or an effective sui generis system or a combination of the two has been controversial. However, developing countries have made surprisingly little use of the freedom to design their own systems in this field. Instead, there has been a surge in UPOV membership among developing countries and some have gone as far as introducing patent protection for plant varieties. Such countries now have to consider the same exclusions and exceptions to patenting that are normally discussed in countries with much more advanced biotechnology industries. The chapter examines the scope for the use of orde public considerations under Article 27.2 TRIPS, of exclusions for research and experimental purposes under Article 30 TRIPS, compulsory licensing under Article 31 TRIPS as well as the advantages of a specific breeding exemption and it briefly comments on the various sui generis options. While liberal interpretations of the TRIPS exceptions remain possible, the chapter concludes that the majority of developing countries will be better off in more creatively using the freedom to develop sui generis systems suitable for their local conditions rather than struggling to introduce TRIPS conform ‘limited exceptions’ to patent protection for plant varieties.

V for variety: Lessons learned from complex smart cities data harmonization and integration

With emerging trends for Internet of Things (IoT) and Smart Cities, complex data transformation, aggregation and visualization problems are becoming increasingly common. These tasks support improved business intelligence, analytics and enduser access to data. However, in most cases developers of these tasks are presented with challenging problems including noisy data, diverse data formats, data modeling and increasing demand for sophisticated visualization support. This paper describes our experiences with just such problems in the context of Household Travel Surveys data integration and harmonization. We describe a common approach for addressing these harmonizations. We then discuss a set of lessons that we have learned from our experience that we hope will be useful for others embarking on similar problems. We also identify several key directions and needs for future research and practical support in this area.

Exploring psychometric properties of the SF-6D, a preference-based health-related quality of life measure, in the context of spinal cord injury

PURPOSE: The validity of the SF-6D, a preference-based measure of health-related quality of life, is not well explored in the context of spinal cord injury (SCI). The aim of this analysis was to assess appropriate measurement properties of the SF-6D in a sample of individuals living with SCI. METHODS: Longitudinal data from the Rick Hansen Spinal Cord Injury Registry were used. Responses to the 36-item short-form health survey were transformed into SF-6D utility scores. We investigated practicality, floor and ceiling effects, and responsiveness to change. Responsiveness to change was explored using three different anchors that reflected changes in self-reported health, functional independence, and life satisfaction. Discriminative validity was assessed by ten a priori defined hypotheses, with a distinction made between 'strong' and 'weak' hypotheses. RESULTS: Three hundred and fifty-eight individuals with SCI were included in this analysis. Practicality was deemed acceptable based on a completion rate of 94%. The SF-6D showed low responsiveness to detect important health changes over time, and differences in responsiveness were found between individuals with paraplegia and tetraplegia. All five strong hypotheses and three weak hypotheses were confirmed. CONCLUSION: The SF-6D demonstrated good practicality and discriminative validity in this sample. The failure to detect self-reported and clinically important health changes requires further consideration. Comparative performance of the SF-6D (i.e., how the SF-6D performs against other preference-based measures) is unknown in the SCI context and requires further research.

Perceptions of individuals living with spinal cord injury toward preference-based quality of life instruments : a qualitative exploration

BACKGROUND: Generic preference-based health-related quality of life instruments are widely used to measure health benefit within economic evaluation. The availability of multiple instruments raises questions about their relative merits and recent studies have highlighted the paucity of evidence regarding measurement properties in the context of spinal cord injury (SCI). This qualitative study explores the views of individuals living with SCI towards six established instruments with the objective of identifying 'preferred' outcome measures (from the perspective of the study participants). METHODS: Individuals living with SCI were invited to participate in one of three focus groups. Eligible participants were identified from Vancouver General Hospital's Spine Program database; purposive sampling was used to ensure representation of different demographics and injury characteristics. Perceptions and opinions were solicited on the following questionnaires: 15D, Assessment of Quality of Life 8-dimension (AQoL-8D), EQ-5D-5L, Health Utilities Index (HUI), Quality of Well-Being Scale Self-Administered (QWB-SA), and the SF-36v2. Framework analysis was used to analyse the qualitative information gathered during discussion. Strengths and limitations of each questionnaire were thematically identified and managed using NVivo 9 software. RESULTS: Major emergent themes were (i) general perceptions, (ii) comprehensiveness, (iii) content, (iv) wording and (v) features. Two sub-themes pertinent to content were also identified; 'questions' and 'options'. All focus group participants (n = 15) perceived the AQoL-8D to be the most relevant instrument to administer within the SCI population. This measure was considered to be comprehensive, with relevant content (i.e. wheelchair inclusive) and applicable items. Participants had mixed perceptions about the other questionnaires, albeit to varying degrees. CONCLUSIONS: Despite a strong theoretical underpinning, the AQoL-8D (and other AQoL instruments) is infrequently used outside its country of origin (Australia). Empirical comparative analyses of the favoured instruments identified in this qualitative study are necessary within the context of spinal cord injury.

Relative preference-based recommender systems

This study investigates the problem of making recommendations to users, such as recommending a movie. Several novel models are proposed to make accurate recommendations by analyzing both the explicit and implicit data. Experiment results have confirmed improvements over state-of-the-art models.

Aggregation and consensus for preference relations based on fuzzy partial orders

We propose a framework for eliciting and aggregating pairwise preference relations based on the assumption of an underlying fuzzy partial order. We also propose some linear programming optimization methods for ensuring consistency either as part of the aggregation phase or as a pre- or post-processing task. We contend that this framework of pairwise-preference relations, based on the Kemeny distance, can be less sensitive to extreme or biased opinions and is also less complex to elicit from experts. We provide some examples and outline their relevant properties and associated concepts.

Preference relation-based Markov Random Fields for recommender systems

A preference relation-based Top-N recommendation approach is proposed to capture both second-order and higher-order interactions among users and items. Traditionally Top-N recommendation was achieved by predicting the item ratings first, and then inferring the item rankings, based on the assumption of availability of explicit feedback such as ratings, and the assumption that optimizing the ratings is equivalent to optimizing the item rankings. Nevertheless, both assumptions are not always true in real world applications. The proposed approach drops these assumptions by exploiting preference relations, a more practical user feedback. Furthermore, the proposed approach enjoys the representational power of Markov Random Fields thus side information such as item and user attributes can be easily incorporated. Comparing to related work, the proposed approach has the unique property of modeling both second-order and higher-order interactions among users and items. To the best of our knowledge, this is the first time both types of interactions have been captured in preference-relation based methods. Experimental results on public datasets demonstrate that both types of interactions have been properly captured, and significantly improved Top-N recommendation performance has been achieved.

"When I saw walking I just kind of took it as wheeling": interpretations of mobility-related items in generic, preference-based health state instruments in the context of spinal cord injury

Background : In health economic analyses, health states are typically valued using instruments with few items per dimension. Due to the generic (and often reductionist) nature of such instruments, certain groups of respondents may experience challenges in describing their health state. This study is concerned with generic, preference-based health state instruments that provide information for decisions about the allocation of resources in health care. Unlike physical measurement instruments, preference-based health state instruments provide health state values that are dependent on how respondents interpret the items. This study investigates how individuals with spinal cord injury (SCI) interpret mobility-related items contained within six preference-based health state instruments.

Methods : Secondary analysis of focus group transcripts originally collected in Vancouver, Canada, explored individuals’ perceptions and interpretations of mobility-related items contained within the 15D, Assessment of Quality of Life 8-dimension (AQoL-8D), EQ-5D-5L, Health Utilities Index (HUI), Quality of Well-Being Scale Self-Administered (QWB-SA), and the 36-item Short Form health survey version 2 (SF-36v2). Ritchie and Spencer’s ‘Framework Approach’ was used to perform thematic analysis that focused on participants’ comments concerning the mobility-related items only.

Results : Fifteen individuals participated in three focus groups (five per focus group). Four themes emerged: wording of mobility (e.g., ‘getting around’ vs ‘walking’), reference to aids and appliances, lack of suitable response options, and reframing of items (e.g., replacing ‘walking’ with ‘wheeling’). These themes reflected item features that respondents perceived as relevant in enabling them to describe their mobility, and response strategies that respondents could use when faced with inaccessible items.

Conclusion : Investigating perceptions to mobility-related items within the context of SCI highlights substantial variation in item interpretation across six preference-based health state instruments. Studying respondents’ interpretations of items can help to understand discrepancies in the health state descriptions and values obtained from different instruments. This line of research warrants closer attention in the health economics and quality of life literature.