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An improvement on the Tracy and Chen model / M. Khalili in Journal of the operational research society (JORS), Vol. 61 N° 12 (Décembre 2010) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 61 N° 12 (Décembre 2010) . - pp. 1789–1793 Titre : An improvement on the Tracy and Chen model : a generalized model for weight restrictions in DEA Type de document : texte imprimé Auteurs : M. Khalili, Auteur ; A. S. Camanho, Auteur ; M. C. A. S. Portela, Auteur Année de publication : 2011 Article en page(s) : pp. 1789–1793 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Data  envelopment  analysis  Relative  efficiency  Generalized  weight  restrictions Index. décimale : 001.424 Résumé : Recently Tracy and Chen presented a parametric DEA model (PDEA) to assess relative efficiency in the presence of a generalized form of linear weight restrictions. This paper proposes a modification to the PDEA model that avoids the need to resort to searching algorithms to estimate efficiency, and assures that the correct efficiency scores are obtained in a single stage using mathematical programming solvers. The results of this model and the results of Tracy and Chen's PDEA model are compared using the examples reported in their paper. The results confirm the superiority of the model proposed in this paper. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v61/n12/abs/jors2009140a.html [article] An improvement on the Tracy and Chen model : a generalized model for weight restrictions in DEA [texte imprimé] / M. Khalili, Auteur ; A. S. Camanho, Auteur ; M. C. A. S. Portela, Auteur . - 2011 . - pp. 1789–1793. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 61 N° 12 (Décembre 2010) . - pp. 1789–1793 Mots-clés : Data  envelopment  analysis  Relative  efficiency  Generalized  weight  restrictions Index. décimale : 001.424 Résumé : Recently Tracy and Chen presented a parametric DEA model (PDEA) to assess relative efficiency in the presence of a generalized form of linear weight restrictions. This paper proposes a modification to the PDEA model that avoids the need to resort to searching algorithms to estimate efficiency, and assures that the correct efficiency scores are obtained in a single stage using mathematical programming solvers. The results of this model and the results of Tracy and Chen's PDEA model are compared using the examples reported in their paper. The results confirm the superiority of the model proposed in this paper. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v61/n12/abs/jors2009140a.html

Analysis of complementary methodologies for the estimation of school value added / M. C. A. S. Portela in Journal of the operational research society (JORS), Vol. 61 N° 7 (Juillet 2010) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 61 N° 7 (Juillet 2010) . - pp. 1122–1132 Titre : Analysis of complementary methodologies for the estimation of school value added Type de document : texte imprimé Auteurs : M. C. A. S. Portela, Auteur ; A. S. Camanho, Auteur Année de publication : 2011 Article en page(s) : pp. 1122–1132 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Efficiency  DEA  Value  added  Secondary  schools Index. décimale : 001.424 Résumé : This paper analyses the value added (VA) of a sample of Portuguese schools using two methodologies: data envelopment analysis (DEA) and the methodology used presently by the UK Department for Children, Schools and Families (DCSF). The VA estimates obtained by the two methods are substantially different. This reflects their different focus: DEA emphasizes on best-observed performance, whereas the DCSF method reveals average performance. The main advantage of the methodology used by the DCSF is its simplicity, although it confounds pupil effects with school effects in the estimation of school VA. In contrast, the DEA methodology can differentiate these effects, but the complexity may prevent its use in a systematic way. This paper shows that the two methods provide complementary information regarding the VA of schools, and their joint use can improve the understanding of the relative effectiveness of schools regarding the progress that pupils make between educational stages. DEWEY : 001.424 ISSN : 0361-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v61/n7/abs/jors200985a.html [article] Analysis of complementary methodologies for the estimation of school value added [texte imprimé] / M. C. A. S. Portela, Auteur ; A. S. Camanho, Auteur . - 2011 . - pp. 1122–1132. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 61 N° 7 (Juillet 2010) . - pp. 1122–1132 Mots-clés : Efficiency  DEA  Value  added  Secondary  schools Index. décimale : 001.424 Résumé : This paper analyses the value added (VA) of a sample of Portuguese schools using two methodologies: data envelopment analysis (DEA) and the methodology used presently by the UK Department for Children, Schools and Families (DCSF). The VA estimates obtained by the two methods are substantially different. This reflects their different focus: DEA emphasizes on best-observed performance, whereas the DCSF method reveals average performance. The main advantage of the methodology used by the DCSF is its simplicity, although it confounds pupil effects with school effects in the estimation of school VA. In contrast, the DEA methodology can differentiate these effects, but the complexity may prevent its use in a systematic way. This paper shows that the two methods provide complementary information regarding the VA of schools, and their joint use can improve the understanding of the relative effectiveness of schools regarding the progress that pupils make between educational stages. DEWEY : 001.424 ISSN : 0361-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v61/n7/abs/jors200985a.html

Productivity change in the water industry in England and Wales / M. C. A. S. Portela in Journal of the operational research society (JORS), Vol. 62 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2173–2188 Titre : Productivity change in the water industry in England and Wales : application of the meta-Malmquist index Type de document : texte imprimé Auteurs : M. C. A. S. Portela, Auteur ; Thanassoulis, E., Auteur ; A. Horncastle, Auteur Année de publication : 2011 Article en page(s) : pp. 2173–2188 Note générale : Recherche opérationnelle Langues : Anglais (eng) Mots-clés : Productivity  Malmquist  index  DEA  Water  companies Index. décimale : 001.424 Résumé : This paper uses a meta-Malmquist index for measuring productivity change of the water industry in England and Wales and compares this to the traditional Malmquist index. The meta-Malmquist index computes productivity change with reference to a meta-frontier, it is computationally simpler and it is circular. The analysis covers all 22 UK water companies in existence in 2007, using data over the period 1993–2007. We focus on operating expenditure in line with assessments in this field, which treat operating and capital expenditure as lacking substitutability. We find important improvements in productivity between 1993 and 2005, most of which were due to frontier shifts rather than catch up to the frontier by companies. After 2005, the productivity shows a declining trend. We further use the meta-Malmquist index to compare the productivities of companies at the same and at different points in time. This shows some interesting results relating to the productivity of each company relative to that of other companies over time, and also how the performance of each company relative to itself over 1993–2007 has evolved. The paper is grounded in the broad theory of methods for measuring productivity change, and more specifically on the use of circular Malmquist indices for that purpose. In this context, the contribution of the paper is methodological and applied. From the methodology perspective, the paper demonstrates the use of circular meta-Malmquist indices in a comparative context not only across companies but also within company across time. This type of within-company assessment using Malmquist indices has not been applied extensively and to the authors’ knowledge not to the UK water industry. From the application perspective, the paper throws light on the performance of UK water companies and assesses the potential impact of regulation on their performance. In this context, it updates the relevant literature using more recent data. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors201117a.html [article] Productivity change in the water industry in England and Wales : application of the meta-Malmquist index [texte imprimé] / M. C. A. S. Portela, Auteur ; Thanassoulis, E., Auteur ; A. Horncastle, Auteur . - 2011 . - pp. 2173–2188. Recherche opérationnelle Langues : Anglais (eng) in Journal of the operational research society (JORS) > Vol. 62 N° 12 (Décembre 2011) . - pp. 2173–2188 Mots-clés : Productivity  Malmquist  index  DEA  Water  companies Index. décimale : 001.424 Résumé : This paper uses a meta-Malmquist index for measuring productivity change of the water industry in England and Wales and compares this to the traditional Malmquist index. The meta-Malmquist index computes productivity change with reference to a meta-frontier, it is computationally simpler and it is circular. The analysis covers all 22 UK water companies in existence in 2007, using data over the period 1993–2007. We focus on operating expenditure in line with assessments in this field, which treat operating and capital expenditure as lacking substitutability. We find important improvements in productivity between 1993 and 2005, most of which were due to frontier shifts rather than catch up to the frontier by companies. After 2005, the productivity shows a declining trend. We further use the meta-Malmquist index to compare the productivities of companies at the same and at different points in time. This shows some interesting results relating to the productivity of each company relative to that of other companies over time, and also how the performance of each company relative to itself over 1993–2007 has evolved. The paper is grounded in the broad theory of methods for measuring productivity change, and more specifically on the use of circular Malmquist indices for that purpose. In this context, the contribution of the paper is methodological and applied. From the methodology perspective, the paper demonstrates the use of circular meta-Malmquist indices in a comparative context not only across companies but also within company across time. This type of within-company assessment using Malmquist indices has not been applied extensively and to the authors’ knowledge not to the UK water industry. From the application perspective, the paper throws light on the performance of UK water companies and assesses the potential impact of regulation on their performance. In this context, it updates the relevant literature using more recent data. DEWEY : 001.424 ISSN : 0160-5682 En ligne : http://www.palgrave-journals.com/jors/journal/v62/n12/abs/jors201117a.html