1,721,036 research outputs found
22. Gentili (B.) et Prato (C). Poetae elegiaci (testimonia et fragmenta), pars 1
No full textSchneider Jean. 22. Gentili (B.) et Prato (C). Poetae elegiaci (testimonia et fragmenta), pars 1. In: Revue des Études Grecques, tome 93, fascicule 442-444, Juillet-décembre 1980. pp. 556-557
Methodology for exploratory analysis of latent factors influencing drivers' behaviour
No full textIn the context of route choice, modeling the process that generates the set of available alternatives in the mind of the individual is a complex and not fully explored issue. Route choice behavior is influenced by variables that are observable, such as travel time and cost, and unobservable, such as attitudes, perceptions, spatial abilities, and network knowledge. In this study, attitudinal data were collected with a web-based survey addressed to individuals who habitually drive from home to work. The paper proposes a methodology to conduct a proper application of factor analysis to the route choice context and describes the preparation of an appropriate data set through measures of internal consistency and sampling adequacy. The paper shows that, for the data set obtained from the web-based survey, six latent constructs affecting driver behavior were extracted and scores of each driver on each factor were calculated
A methodology for an exploratory analysis of latent factors influencing drivers' behaviour
No full textIn the context of route choice, modeling the process that generates the set of available alternatives in the mind of the individual is a complex and not fully explored issue. Route choice behavior is influenced by variables that are observable, such as travel time and cost, and unobservable, such as attitudes, perceptions, spatial abilities, and network knowledge. In this study, attitudinal data were collected with a web-based survey addressed to individuals who habitually drive from home to work. The paper proposes a methodology to conduct a proper application of factor analysis to the route choice context and describes the preparation of an appropriate data set through measures of internal consistency and sampling adequacy. The paper shows that, for the data set obtained from the web-based survey, six latent constructs affecting driver behavior were extracted and scores of each driver on each factor were calculated
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Estimating Route Choice Models from Stochastically Generated Choice Sets on Large-Scale Networks. Correcting for Unequal Sampling Probability
No full textRoute choice is one of the most complex decision-making contexts to
represent mathematically, and the most frequently used approach to
model route choice consists of generating alternative routes and modeling
the preferences of utility-maximizing travelers. The main drawback
of this approach is the dependency of the parameter estimates from
the choice set generation technique. Bias introduced in model estimation
has been corrected only for the random walk algorithm, which has
problematic applicability to large-scale networks. This study proposes
a correction term for the sampling probability of routes extracted with
stochastic route generation. The term is easily applicable to large-scale
networks and various environments, given its dependence only on a random
number generator and the Dijkstra shortest path algorithm. The
implementation for revealed preferences data, which consist of actual
route choices collected in Cagliari, Italy, shows the feasibility of generating
routes stochastically in a high-resolution network and calculating
the correction factor. The model estimation with and without correction
illustrates how the correction not only improves the goodness of fit but
also turns illogical signs for parameter estimates to logical signs
Latent variables and route choice behaviour.
No full textIn recent years, a broad array of disciplines (psychology, economics, marketing, public policy and transportation engineering) have shown a general interest in enhancing discrete choice models by considering, within the framework of the choice process, the influence of latent constructs such as attitudes, preferences, perceptions, context and knowledge of the choice environment.
In the route choice context, the representation of individual behavior accounts generally for travel times and costs of alternative routes. Incomplete information about traffic patterns, heterogeneity among drivers in terms of travel time perceptions, and influence of unobservable individual traits motivate the research for improved models, which are able to account for behavioral factors that are likely to affect the choice process.
This paper intends to provide more insight into the analysis of route choice behavior, by considering the influence of latent factors on the choice of a route from a set of available alternatives. First, the measurement of behavioral constructs at the individual level is proposed, by applying exploratory factor analysis to attitudinal indicators collected with a dedicated web-based survey. Then, the generation of alternative routes is considered, by implementing a technique that accounts for behavioral constraints while solving the path enumeration problem. Last, the analysis of route choice behavior is presented, by estimating an innovative model that combines latent variable and discrete choice models.
Data collection focused on individuals who move regularly from home to work in an urban network and agreed to participate in a web-based questionnaire. The first part of the questionnaire consisted of forty-one Likert-type questions, divided into four sections: classification of the respondent, investigation of spatial abilities connected to transportation tasks, exploration of spatial abilities not related to transportation tasks, examination of driving attitudes and preferences. The second part of the questionnaire collected routes considered by the respondents to drive from home to the workplace.
Initial data elaboration considered a dataset cleaned by eliminating incomplete observations in either of the two parts. The application of appropriate statistical methods for ordinal data analysis provided preliminary information about the sample. Tests of internal consistency and sampling adequacy evaluated the suitability of the dataset to exploratory factor analysis. Most relevantly, the extraction of orthogonal latent factors and the examination of factor loadings enabled to observe the most significant relationships between indicators and latent variables, and consequently to define structural and measurement equations for the latent variable model to be integrated with the discrete choice model.
Path generation concentrated on a path enumeration method based on behavioral constraints, rather than on techniques based on variations to the shortest path search. This paper presents a variation of an existing branch and bound algorithm for constrained path enumeration, in order to account for the theory that travelers develop their network knowledge by following a transition from landmark recognition to path definition and relationship definition within the path area. Specifically, the modification concerns the branching rule of the algorithm, which excludes from consideration paths that are highly similar to alternatives in the same area because they share a number of landmarks. This rule extends the concept of similarity between routes from the physical sharing of a number of links to the physical sharing of a number of anchorpoints through which travelers define their routes.
Choice modeling focused on the estimation of an integrated latent variable and discrete choice model, through an approach that analyzes latent factors able to provide valuable information on aspects of route choice behavior that cannot be inferred only from revealed preferences. The model framework considers observable explanatory variables and latent factors to affect individual preferences toward alternatives, and assumes these preferences as latent variables representing the desirability of alternative choices. Further, the model framework considers the actual chosen routes as manifestations of the latent preferences, and the responses to the survey questions as indicators of the latent factors.
Accordingly, the integrated latent variable and discrete choice model consists of structural and measurement equations. Structural equations relate the observable variables to the latent factors and to the utilities. Measurement equations relate the latent factors to the indicators and the utilities to the latent preferences. The model is estimated through the maximization of a likelihood function that is the integral of the choice model over the distribution of the latent constructs. The choice model portion of the likelihood function is a Path Size Logit model, since this specification allows to account for similarities among alternatives while maintaining the simple Logit structure. The latent variable portion of the likelihood function assumes that latent variables are orthogonal (as observed in the exploratory factor analysis) and indicators are assumed to be independent, conditionally on the observed variables.
Results confirm the initial hypothesis that considering attitudes and perceptions allows better representation of route choice behavior, as relevant factors such as habit, travel time perception and familiarity with the choice environment are as important as observable variables such as travel time and distance, traditionally considered in any route choice study. From a broader perspective, results suggest the correctness of the suggestion of behavioral researchers to give importance to psychological and cognitive aspects inside the choice processes, and not to consider discrete choice models as black boxes in which the inputs are only the attributes of available alternatives and individual characteristics, and the outputs are the observed choices
Reference Points and Democratic Backsliding
Full text linkWe propose a theory of democratic backsliding where citizens' retrospective assessment of an incumbent politician depends on expectations that are endogenous to the incumbent's behaviour. We show that democratic backsliding can occur even when most citizens and most politicians intrinsically value democracy. By challenging norms of democracy, an incumbent can lower citizens' expectations; by not doubling down on this challenge, he can then beat this lowered standard. As a result, gradual backsliding can actually enhance an incumbent's popular support not despite but because of citizens' opposition to backsliding. This mechanism can only arise when citizens are uncertain enough about incumbents' preferences (e.g. owing to programmatically weak parties). Mass polarization, instead, can reduce the occurrence of backsliding while simultaneously increasing its severity
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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