1,721,035 research outputs found
Dynamic cost efficiency in port infrastructure using a directional distance function: accounting for the adjustment of quasi-fixed inputs over time
No full textThis paper analyzes dynamic efficiency in ports. Using parametric techniques we estimate a stochastic cost frontier to measure overall long-run cost efficiency and an input-oriented directional distance to measure dynamic technical efficiency for a set of 26 Spanish port authorities observed over the period 1993-2012. Technical inefficiency is conceived as the ability of ports to simultaneously expand gross investment and contract variable inputs while maintaining output constant. Ports in this framework are assumed to invest with a view to minimizing the present value of future production costs. Our results show that ports could achieve long-run cost savings of over 38%, two-thirds of which could be achieved by reducing input use and the remainder to changing the input-mix used.3042963,3123,338Q1Q1SCIESSC
Can ports increase traffic while reducing inputs? Technical efficiency of Spanish Port Authorities using a directional distance function approach
No full textThe focus of this paper is on the productive efficiency of ports. We estimate a directional technology distance function using parametric techniques to analyze the production technology and technical efficiency of a set of Spanish Port Authorities observed over the period 1993-2012. Technical inefficiency is conceived as the ability of ports to simultaneously expand a given output and contract variable inputs while maintaining quasi-fixed inputs and other outputs constant. Thus, for containerized cargo we address the following question: Given the amount of quasi-fixed inputs used by the firm and given the volume of the other outputs (liquids, solids, non-containerized cargo and passenger traffic), could ports increase their containerized merchandise while simultaneously reducing their variable inputs? Similar questions are asked for solid bulk and non-containerized general cargo. Our results show evidence of technical inefficiency among the ports in our sample. In particular, if the ports operated efficiently, we find that containerized cargo could be expanded by an average of over 6.4%, with an equivalent reduction in variable inputs. Solid bulk cargo and general non-containerized cargo could be increased by 4.1% and 6.1% respectively, with corresponding reductions in variable inputs. An implication of our results is that there is ample scope for specialization on the part of ports with no increase in infrastructure costs. Given that large investments in infrastructure have been made in Spanish port over the last decade, this opens the possibility of moving towards a management model based on taking advantage of existing capacity rather than new investments.1401281,7811,994Q1Q1SCIESSC
The impact of demand uncertainty on port infrastructure costs: Useful information for regulators?
No full textRecent changes to regulation legislation permit Spanish ports more autonomy and a degree of control over pricing policy. This implies a shift in emphasis away from investments in new infrastructure and towards focusing on demand and taking full advantage of existing assets. The degree to which ports can modify tariffs depends, among other things, on forecasts of traffic, debt levels, objective annual profitability and reasonable yields on assets. Insofar as demand uncertainty affects ports[U+05F3] costs, this will affect ports[U+05F3] ability to meet efficiency and profitability targets. We analyze the effects of demand uncertainty of port costs using a panel data set of 26 Spanish port authorities observed over the period 1993-2007. Estimating a cost function using panel data techniques, we find a significant effect of demand on costs. Non-containerized general cargo was the service whose demand variability most affected port costs. We quantify the effects of demand variability on costs using a simple counterfactual exercise. On the basis of our results we find that if ports in Spain faced the same relative demand variability as the port with the lowest relative demand variability, as measured by coefficients of variation of demand, costs would be an average of 2-3% lower depending on the specification of demand. Different demand variabilities among ports should therefore be taken into consideration by regulators for pricing policy and when imposing minimum profit requirements on ports.1831761,481,492Q1Q1SSC
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Specialisation, diversification, size and technical efficiency in ports: an empirical analysis using frontier techniques
Get PDFThis paper explores the relationship between output specialisation, diversification, size and technical efficiency in ports. Using a sample of Spanish port authorities observed over the period 1993-2012, we calculate a normalised Herfindahl-Hirschman index of overall specialisation and indices of relative specialisation in the individual cargoes. An output distance frontier is estimated using non-parametric Data Envelopment Analysis techniques to calculate technical efficiency. These efficiency scores are then used to test that relationship with a bootstrapped truncated regression. We find that both overall and relative output specialisation have a positive influence on technical efficiency. Moreover, the positive effects of specialisation on technical efficiency is reinforced for larger ports, which are in a better position to take advantage of economies of scale and which can also attract different types of cargo (enjoying also economies of scope) and therefore protect themselves from adverse demand conditions. Our results underline the trade-off for smaller port authorities between efficiency gains from specialisation and their vulnerability to market conditions for their main output
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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