1,720,982 research outputs found
Panel Data Econometrics in R: The plm Package
Full text linkPanel data econometrics is obviously one of the main fields in the profession, but most of the models used are difficult to estimate with R. plm is a package for R which intends to make the estimation of linear panel models straightforward. plm provides functions to estimate a wide variety of models and to make (robust) inference.
Fonction de demande et surplus : une estimation sur des données de panel pour les transports urbains français
No full textDemand and surplus functions: estimates based on panel data for French urban transport
by Yves Croissant
In this article, we present the estimation of a demand function for urban transportation. This is a translog demand function which takes into account income redistribution and which is estimated using panel data for France. Price and income elasticities obtained here are consistent with previous results. Using a flexible functional demand function enables us to construct a surplus function obtained by integration of the demand function.Fonction de demande et surplus : une estimation sur des données de panel pour les transports
urbains français par Yves Croissant
Cet article présente l'estimation d'une fonction de demande pour les transports urbains. Il s'agit d'une fonction de type translog qui prend en compte la distribution des revenus et qui est estimée sur données de panel françaises. Les élasticités par rapport au prix et à la qualité sont conformes à celles obtenues habituellement. L'intérêt d'utiliser une forme flexible est de pouvoir construire par intégration de la demande une fonction de surplus.Croissant Yves. Fonction de demande et surplus : une estimation sur des données de panel pour les transports urbains français. In: Économie & prévision, n°145, 2000-4. pp. 53-66
Extended Model Formulas in R: Multiple Parts and Multiple Responses
Full text linkModel formulas are the standard approach for specifying the variables in statistical models in the S language. Although being eminently useful in an extremely wide class of applications, they have certain limitations including being confined to single responses and not providing convenient support for processing formulas with multiple parts. The latter is relevant for models with two or more sets of variables, e.g., different equations for different model parameters (such as mean and dispersion), regressors and instruments in instrumental variable regressions, two-part models such as hurdle models, or alternative-specific and individual-specific variables in choice models among many others. The R package Formula addresses these two problems by providing a new class âÂÂFormulaâ (inheriting from âÂÂformulaâÂÂ) that accepts an additional formula operator | separating multiple parts and by allowing all formula operators (including the new |) on the left-hand side to support multiple responses.
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
2012), Estimation of multinomial logit models in R : The mlogit Package. R package version 0.2-2. URL: http://cran. r-project.org/web/packages/mlogit/vignettes/mlogit.pdf
No full textmlogit is a package for R which enables the estimation of the multinomial logit models with individual and/or alternative specific variables. The main extensions of the basic multinomial model (heteroscedastic, nested and random parameter models) are implemented. Keywords:˜discrete choice models, maximum likelihood estimation, R, econometrics. An introductory example The logit model is useful when one tries to explain discrete choices, i.e. choices of one among several mutually exclusive alternatives1. There are many useful applications of discrete choice modelling in different fields of applied econometrics, using individual data, which may be: revealed preferences data which means that the data are observed choices of indi-viduals for, say, a transport mode (car, plane and train for example), stated preferences data; in this case, individuals face a virtual situation of choice, for example the choice between three train tickets with different characteristics: – A: a train ticket which costs 10 euros, for a trip of 30 minutes and one change, – B: a train ticket which costs 20 euros, for a trip of 20 minutes and no change, – C: a train ticket which costs 22 euros, for a trip of 22 minutes and one change. Suppose that, in a transport mode situation, we can define an index of satisfaction Vj for each alternative which depends linearly on cost (x) and time (z): V1 = α1 + βx1 + γz1 V2 = α2 + βx2 + γz2 V3 = α3 + βx3 + γz3 1For an extensive presentations of the logit model, see Train (2003) and Louiviere, Hensher, and Swait (2000) Yves Croissant 2 In this case, the probability of choosing the alternative j is increasing with Vj. For sake of estimation, one has to transform the satisfaction index, which can take any real value so that it is restricted to the unit interval and can be interpreted as a probability. The multinomial logit model is obtained by applying such a transformation to the Vjs. More specifically, we have: P1 = eV1 eV1+eV2+eV3 P2 = eV2 eV1+eV2+eV3 P3 = eV3 eV1+eV2+eV3 The two characteristics of probabilities are satisfied
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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