1,720,979 research outputs found
An Improved procedure for Bootstrapping Malmquist Indices and its applications on the regional economic growth
Full text linkEstendendo l’approccio di decomposizione dell’Indice di Malmquist proposto da Fare et al. (1992) secondo cui la variazione della produttività è descritta come variazione della tecnologia e dell’efficienza, Simar e Wilson (1999) hanno fornito per la prima volta un’interpretazione statistica dell’indice e dei suoi componenti, proponendo un algoritmo basato sul bootstrap per stimare gli intervalli di confidenza degli indici sopra definiti.
In questa tesi si è, per la prima volta, proposto un nuovo metodo di stima della densità, basato su una selezione più accurata della bandwidth, partendo e adattando i recenti sviluppi introdotti da Simar e Wilson (2007) nel caso univariato al caso bivariato. Inoltre, per la prima volta è stata testata la performance delle procedure per stimare gli indici, attraverso l’implementazione di simulazioni Monte Carlo. Essi hanno mostrato un basso livello di performance del modello proposto da Simar e Wilson nel 1999 rispetto a quello proposto in questo lavoro. In particolare, essi hanno evidenziato che la procedura di stima della densità è molto sensibile alla presenza di valori unitari dell’efficienza, tanto da fornire seri problemi nella valutazione della stima della funzione di densità continua. Inoltre, sono stati applicati e adattati i data driven methods, che hanno evidenziato risultati diversi rispetto alla procedura originale, lasciano ampi spazi a ricerche future.
Da un punto di vista empirico, è stata analizzata la crescita delle regioni italiane attraverso la Total Factor Productivity (TFP), nel periodo 1980-2001. Quindi sono stati stimati l’indice di Malmquist e i suoi componenti come pure i loro rispettivi intervalli di confidenza, applicando la procedure migliore, identificata nella fase di ricerca precedente. E’ stato registrato un guadagno complessivo della variazione della produttività, corretta nella bias, del 2.1%, dell’efficienza del 0.5% e della tecnologia del 1.6%. L’analisi di sensibilità, basata su tecniche bootstrap, ha rilevato che per la maggior parte delle regioni italiane l’efficienza e la tecnologia non hanno mostrato cambiamenti statisticamente significativi. Secondo questi risultati, l’approccio inferenziale ha fornito un’analisi più accurata e rigorosa rispetto all’approccio tradizionale, adottato da Leonida et al.(2004 ,Table 1, pg. 2190) nella quale le stime sono state valutate come miglioramenti o recessioni, trascurando sia la correzione della bias che il loro significato statistico.Improving the Fare et al. (1992) approach on Malmquist index of productivity, which can be decomposed into indices describing changes in technology and changes in efficiency , Simar and Wilson (1999) provided a statistical interpretation to their Malmquist productivity index and its components, and presented a bootstrap algorithm to estimate confidence intervals for the indices.
Extending the recent developments introduced by Simar and Wilson (2007) in the bandwidth specification in the univariate case, we propose new methods of density estimation, based on more accurate bandwidth specification. Monte Carlo experiments have been computed for the first time in this context. They have shown a low quality of performance of the Simar and Wilson (1999)'s bootstrap approximations, and high level of quality for the proposed methods. In particular, they have found out as best performer method the procedure based on the density estimation without considering the ones, revealing the severe problem of deteriorating the estimation of the continuous density of the efficiency scores. Moreover, data driven methods have been applied to the Malmquist Index framework and at this stage of research they have shown different results from those provided by Simar and Wilson (1999).
From an empirical point of view, Total Factor Productivity (TFP) growth of the Italian regions over the period 1980-2001 has been analyzed. Malmquist Productivity Index (MPI) and its components (namely Efficiency Change and Technical Change) as well as confidence intervals have been estimated by applying the best performed procedure, previously determinated. Including human capital among inputs, we estimated
an overall bias-corrected productivity gain of 2.1 percent, an efficiency gain of 0.5 and a technical gain of 1.6 percent. The bootstrap analysis revealed that for most Italian regions efficiency and technical changes did not show a statistically significant change. According to these results, the inferential approach has provided a more rigorous and accurate insights on the Italian regional TFP than the traditional Data Envelopment
Analysis (DEA) estimation carried out by Leonida et al.(2004 ,Table 1, pg. 2190) in which all the estimated values are interpreted as progress or regress without taking into account the bias of the estimated values and their statistical significance
Is Telecommunications Productivity Characterized by Steady State Conditions? Some empirical evidence for 13 OECD countries
No full textThe Italian airport industry in transition: a performance analysis
No full textThis paper analyzes the impacts of Italian government actions on the efficiency of 36 airports between 2001 and 2003 The changes have included privatization, enlargement of the services provided directly by airport management companies, through the modification of the concession agreements, and the creation of two hubs. The analysis, using the consolidated two-stage data envelopment analysis with bootstrapping, indicates that airports with a majority public holding are on average more efficient and the presence of two hubs is source of inefficiency (C) 2009 Elsevier Ltd All rights reserve
Measuring the technical efficiency of French TTOs: first insights
No full textThis paper uses an original and detailed dataset (managed by the BETA for the French Ministry of Education and Research) which collects two comprehensive surveys on French universities’ TTOs to shed light on the functioning of French TTOs.
The sample is made by various inputs and outputs of around 80 French university TTOs over the period 2000-2005. The dataset includes revenue from R&D contracts, university revenue from basic research, number of TTO’s technical personnel specialized in R&D contracts and, annual budget of TTOs.
The main contribution of the paper is then to assess quantitatively and in a rigorous way the performance of French TTOs, by using a bootstrap-based non parametric approach (for details see Daraio and Simar, 2007). The issue is of high policy relevance and well recognized by policymakers and university managers as one of the engines of economic growth
Un’applicazione della Data Envelopment Analysis (DEA) per la misurazione dell’efficienza degli aeroporti italiani dopo la privatizzazione del settore.
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New evidence on the efficiency of Italian airports: a bootstrapped DEA analysis
No full textA bootstrapped DEA procedure is used to estimate technical efficiency of 18 Italian airports during the period 2000-2004. Departing from previous studies, we separate the efficiency related to ability to manage airside activities (operational) from that related to the management of all business activities (financial). In general, Italian airports operate at poor levels of efficiency, with slightly better performance in terms of their financial activities. In the current study, selected intrinsic and environmental characteristics are considered as possible drivers of Italian airport performance. In particular, we found that: (i) the airport dimension does not allows for operational efficiency advantages, (ii) on the other hand, the airport dimension allows for financial efficiency advantages for the case of hubs and disadvantages for the case of the smallest airports (iii) the type(s) of concession agreement(s) might be considered as important source of technical efficiency differentials for those airports running marginal commercial activities; (iv) the introduction of a dual-till price cap regulation might create incentives which lead to the increase of financial efficiency at the detriment of the operational performance. Lastly, the development of a second hub (Milano Malpensa), has negatively affected the performance of the country's national hub (Roma Fiumicino)
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
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