IDEAS home Printed from https://ideas.repec.org/a/eee/glofin/v46y2020ics1044028318302977.html
   My bibliography  Save this article

Estimating risk efficiency in Middle East banks before and after the crisis: A metafrontier framework

Author

Listed:
  • Colesnic, Olga
  • Kounetas, Konstantinos
  • Michael, Polemis

Abstract

The aim of this study is three-fold. Firstly, it attempts to analyse the effect of risk on Middle East banks' efficiency levels before and after the recent financial crisis. Secondly, it seeks to determine the influence of bank size taking into consideration the possible inefficiency originated to risk abatement cost. Thirdly, it investigates the possible effect of oil price shocks on banks' performance. To examine these issues we introduce a risk efficiency index based on an output orientated directional distance function with weak and strong disposability assumptions. The methodology has been applied on a panel of Middle East banks spanning the period 1998–2014.The empirical findings suggest that on average small banks are more efficient and their size has less negative impact on their technical efficiency and risk management. On the other hand, large banks' risk management is found to be more flexible during the financial crisis. Moreover, banks with higher fixed assets are associated with more costly disposals of non-performing loans justifying the rejection of a positive relation between bank size and technical efficiency. Finally, oil price shocks play a significant role.

Suggested Citation

  • Colesnic, Olga & Kounetas, Konstantinos & Michael, Polemis, 2020. "Estimating risk efficiency in Middle East banks before and after the crisis: A metafrontier framework," Global Finance Journal, Elsevier, vol. 46(C).
  • Handle: RePEc:eee:glofin:v:46:y:2020:i:c:s1044028318302977
    DOI: 10.1016/j.gfj.2019.100484
    as

    Download full text from publisher

    File URL: http://www.sciencedirect.com/science/article/pii/S1044028318302977
    Download Restriction: Full text for ScienceDirect subscribers only

    File URL: https://libkey.io/10.1016/j.gfj.2019.100484?utm_source=ideas
    LibKey link: if access is restricted and if your library uses this service, LibKey will redirect you to where you can use your library subscription to access this item
    ---><---

    As the access to this document is restricted, you may want to look for a different version below or search for a different version of it.

    Other versions of this item:

    References listed on IDEAS

    as
    1. Maudos, Joaquin & Pastor, Jose M. & Perez, Francisco & Quesada, Javier, 2002. "Cost and profit efficiency in European banks," Journal of International Financial Markets, Institutions and Money, Elsevier, vol. 12(1), pages 33-58, February.
    2. Shaffer, Sherrill, 2004. "Comment on "What Drives Bank Competition? Some International Evidence" by Stijn Claessens and Luc Laeven," Journal of Money, Credit and Banking, Blackwell Publishing, vol. 36(3), pages 585-592, June.
    3. Arellano, Manuel & Bover, Olympia, 1995. "Another look at the instrumental variable estimation of error-components models," Journal of Econometrics, Elsevier, vol. 68(1), pages 29-51, July.
    4. Hirofumi Fukuyama & William Weber, 2015. "Measuring Japanese bank performance: a dynamic network DEA approach," Journal of Productivity Analysis, Springer, vol. 44(3), pages 249-264, December.
    5. Sara G. Castellanos & Gustavo A. Ángel & Jesús G. Garza-García, 2016. "Competition and Efficiency in the Mexican Banking Industry," Palgrave Macmillan Books, Palgrave Macmillan, number 978-1-137-51841-5, December.
    6. Mester, Loretta J., 1997. "Measuring efficiency at U.S. banks: Accounting for heterogeneity is important," European Journal of Operational Research, Elsevier, vol. 98(2), pages 230-242, April.
    7. Kounetas, Konstantinos, 2015. "Heterogeneous technologies, strategic groups and environmental efficiency technology gaps for European countries," Energy Policy, Elsevier, vol. 83(C), pages 277-287.
    8. Fatemi, Ali & Fooladi, Iraj & Tehranian, Hassan, 2015. "Valuation effects of corporate social responsibility," Journal of Banking & Finance, Elsevier, vol. 59(C), pages 182-192.
    9. Andrieş, Alin Marius & Căpraru, Bogdan, 2014. "The nexus between competition and efficiency: The European banking industries experience," International Business Review, Elsevier, vol. 23(3), pages 566-579.
    10. Berger, Allen N. & Mester, Loretta J., 1997. "Inside the black box: What explains differences in the efficiencies of financial institutions?," Journal of Banking & Finance, Elsevier, vol. 21(7), pages 895-947, July.
    11. Chiu, Ching-Ren & Chiu, Yung-Ho & Chen, Yu-Chuan & Fang, Chen-Ling, 2016. "Exploring the source of metafrontier inefficiency for various bank types in the two-stage network system with undesirable output," Pacific-Basin Finance Journal, Elsevier, vol. 36(C), pages 1-13.
    12. Fiordelisi, Franco & Marques-Ibanez, David & Molyneux, Phil, 2011. "Efficiency and risk in European banking," Journal of Banking & Finance, Elsevier, vol. 35(5), pages 1315-1326, May.
    13. Tsekouras, Kostas & Chatzistamoulou, Nikos & Kounetas, Kostas, 2017. "Productive performance, technology heterogeneity and hierarchies: Who to compare with whom," International Journal of Production Economics, Elsevier, vol. 193(C), pages 465-478.
    14. Berger, Allen N. & Miller, Nathan H. & Petersen, Mitchell A. & Rajan, Raghuram G. & Stein, Jeremy C., 2005. "Does function follow organizational form? Evidence from the lending practices of large and small banks," Journal of Financial Economics, Elsevier, vol. 76(2), pages 237-269, May.
    15. Beccalli, Elena, 2004. "Cross-country comparisons of efficiency: Evidence from the UK and Italian investment firms," Journal of Banking & Finance, Elsevier, vol. 28(6), pages 1363-1383, June.
    16. Nobuyoshi Yamori & Kozo Harimaya & Kei Tomimura, 2017. "Corporate governance structure and efficiencies of cooperative banks," International Journal of Finance & Economics, John Wiley & Sons, Ltd., vol. 22(4), pages 368-378, October.
    17. Nemanja Radić & Franco Fiordelisi & Claudia Girardone, 2012. "Efficiency and Risk-Taking in Pre-Crisis Investment Banks," Journal of Financial Services Research, Springer;Western Finance Association, vol. 41(1), pages 81-101, April.
    18. Mamatzakis, E. & Staikouras, C. & Koutsomanoli-Fillipaki, N., 2005. "Competition and concentration in the banking sector of the South Eastern European region," Emerging Markets Review, Elsevier, vol. 6(2), pages 192-209, June.
    19. Casu, Barbara & Girardone, Claudia, 2009. "Testing the relationship between competition and efficiency in banking: A panel data analysis," Economics Letters, Elsevier, vol. 105(1), pages 134-137, October.
    20. Anzoategui Diego & Martinez Peria Maria S. & Rocha Roberto R, 2010. "Bank Competition in the Middle East and Northern Africa Region," Review of Middle East Economics and Finance, De Gruyter, vol. 6(2), pages 26-48, November.
    21. Tan, Yong & Floros, Christos, 2018. "Risk, competition and efficiency in banking: Evidence from China," Global Finance Journal, Elsevier, vol. 35(C), pages 223-236.
    22. Picazo-Tadeo, Andres J. & Reig-Martinez, Ernest & Hernandez-Sancho, Francesc, 2005. "Directional distance functions and environmental regulation," Resource and Energy Economics, Elsevier, vol. 27(2), pages 131-142, June.
    23. Drake, Leigh & Hall, Maximilian J. B., 2003. "Efficiency in Japanese banking: An empirical analysis," Journal of Banking & Finance, Elsevier, vol. 27(5), pages 891-917, May.
    24. Barbara Casu & Philip Molyneux, 2003. "A comparative study of efficiency in European banking," Applied Economics, Taylor & Francis Journals, vol. 35(17), pages 1865-1876.
    25. Barbara Casu & Alessandra Ferrari & Tianshu Zhao, 2013. "Regulatory Reform and Productivity Change in Indian Banking," The Review of Economics and Statistics, MIT Press, vol. 95(3), pages 1066-1077, July.
    26. Avkiran, Necmi Kemal, 1999. "The evidence on efficiency gains: The role of mergers and the benefits to the public," Journal of Banking & Finance, Elsevier, vol. 23(7), pages 991-1013, July.
    27. Apergis, Nicholas & Fafaliou, Irene & Polemis, Michael L., 2016. "New evidence on assessing the level of competition in the European Union banking sector: A panel data approach," International Business Review, Elsevier, vol. 25(1), pages 395-407.
    28. Watanabe, Michio & Tanaka, Katsuya, 2007. "Efficiency analysis of Chinese industry: A directional distance function approach," Energy Policy, Elsevier, vol. 35(12), pages 6323-6331, December.
    29. Canan Yildirim, 2002. "Evolution of banking efficiency within an unstable macroeconomic environment: the case of Turkish commercial banks," Applied Economics, Taylor & Francis Journals, vol. 34(18), pages 2289-2301.
    30. Tan, Yong, 2017. "The impacts of competition and shadow banking on profitability: Evidence from the Chinese banking industry," The North American Journal of Economics and Finance, Elsevier, vol. 42(C), pages 89-106.
    31. Beck, Thorsten & Demirguc-Kunt, Asli & Levine, Ross, 2006. "Bank concentration, competition, and crises: First results," Journal of Banking & Finance, Elsevier, vol. 30(5), pages 1581-1603, May.
    32. Michael L. Polemis, 2014. "Did financial crisis alter the level of competition in the EMU banks?," Applied Economics Letters, Taylor & Francis Journals, vol. 21(15), pages 1065-1069, October.
    33. Kontolaimou, Alexandra & Kounetas, Konstantinos & Mourtos, Ioannis & Tsekouras, Kostas, 2012. "Technology gaps in European banking: Put the blame on inputs or outputs?," Economic Modelling, Elsevier, vol. 29(5), pages 1798-1808.
    34. Barros, Carlos Pestana & Managi, Shunsuke & Matousek, Roman, 2012. "The technical efficiency of the Japanese banks: Non-radial directional performance measurement with undesirable output," Omega, Elsevier, vol. 40(1), pages 1-8, January.
    35. Anastasia Koutsomanoli-Filippaki & Dimitris Margaritis & Christos Staikouras, 2012. "Profit efficiency in the European Union banking industry: a directional technology distance function approach," Journal of Productivity Analysis, Springer, vol. 37(3), pages 277-293, June.
    36. Fulvio Castellacci, 2011. "Closing the Technology Gap?," Review of Development Economics, Wiley Blackwell, vol. 15(1), pages 180-197, February.
    37. Delis, Manthos D. & Tsionas, Efthymios G., 2009. "The joint estimation of bank-level market power and efficiency," Journal of Banking & Finance, Elsevier, vol. 33(10), pages 1842-1850, October.
    38. Färe, Rolf & Grosskopf, Shawna, 2013. "DEA, directional distance functions and positive, affine data transformation," Omega, Elsevier, vol. 41(1), pages 28-30.
    39. Christopher O’Donnell & D. Rao & George Battese, 2008. "Metafrontier frameworks for the study of firm-level efficiencies and technology ratios," Empirical Economics, Springer, vol. 34(2), pages 231-255, March.
    40. Yujiro Hayami, 1969. "Resource Endowments and Technological Change in Agriculture: U.S. and Japanese Experiences in International Perspective," American Journal of Agricultural Economics, Agricultural and Applied Economics Association, vol. 51(5), pages 1293-1303.
    41. Kounetas, Konstantinos & Mourtos, Ioannis & Tsekouras, Konstantinos, 2009. "Efficiency decompositions for heterogeneous technologies," European Journal of Operational Research, Elsevier, vol. 199(1), pages 209-218, November.
    42. Raéf Bahrini, 2017. "Efficiency Analysis of Islamic Banks in the Middle East and North Africa Region: A Bootstrap DEA Approach," IJFS, MDPI, vol. 5(1), pages 1-13, February.
    43. Yong Tan & John Anchor, 2017. "Does competition only impact on insolvency risk? New evidence from the Chinese banking industry," International Journal of Managerial Finance, Emerald Group Publishing Limited, vol. 13(3), pages 332-354, June.
    44. Yong Tan & Christos Floros & John Anchor, 2017. "The profitability of Chinese banks: impacts of risk, competition and efficiency," Review of Accounting and Finance, Emerald Group Publishing Limited, vol. 16(1), pages 86-105, February.
    45. Nicholas Apergis & Michael L. Polemis, 2016. "Competition and efficiency in the MENA banking region: a non-structural DEA approach," Applied Economics, Taylor & Francis Journals, vol. 48(54), pages 5276-5291, November.
    46. Ramakrishnan Ramanathan, 2007. "Performance of banks in countries of the Gulf Cooperation Council," International Journal of Productivity and Performance Management, Emerald Group Publishing Limited, vol. 56(2), pages 137-154, January.
    47. Tsekouras, Kostas & Chatzistamoulou, Nikos & Kounetas, Kostas & Broadstock, David C., 2016. "Spillovers, path dependence and the productive performance of European transportation sectors in the presence of technology heterogeneity," Technological Forecasting and Social Change, Elsevier, vol. 102(C), pages 261-274.
    48. Michael L. Polemis, 2015. "Does Monopolistic Competition Exist In The Mena Region? Evidence From The Banking Sector," Bulletin of Economic Research, Wiley Blackwell, vol. 67(S1), pages 74-96, December.
    49. Degl'Innocenti, Marta & Kourtzidis, Stavros A. & Sevic, Zeljko & Tzeremes, Nickolaos G., 2017. "Bank productivity growth and convergence in the European Union during the financial crisis," Journal of Banking & Finance, Elsevier, vol. 75(C), pages 184-199.
    50. Kumar, Surender & Khanna, Madhu, 2009. "Measurement of environmental efficiency and productivity: a cross-country analysis," Environment and Development Economics, Cambridge University Press, vol. 14(4), pages 473-495, August.
    51. George Battese & D. Rao & Christopher O'Donnell, 2004. "A Metafrontier Production Function for Estimation of Technical Efficiencies and Technology Gaps for Firms Operating Under Different Technologies," Journal of Productivity Analysis, Springer, vol. 21(1), pages 91-103, January.
    52. Casu, Barbara & Ferrari, Alessandra & Girardone, Claudia & Wilson, John O.S., 2016. "Integration, productivity and technological spillovers: Evidence for eurozone banking industries," European Journal of Operational Research, Elsevier, vol. 255(3), pages 971-983.
    53. Luis Gutiérrez de Rozas, 2007. "Testing for competition in the Spanish banking industry: The Panzar-Rosse approach revisited," Working Papers 0726, Banco de España.
    54. Barbara Casu & Claudia Girardone, 2006. "Bank Competition, Concentration And Efficiency In The Single European Market," Manchester School, University of Manchester, vol. 74(4), pages 441-468, July.
    55. Halkos, George Emm. & Tzeremes, Nickolaos G., 2011. "Modelling the effect of national culture on multinational banks' performance: A conditional robust nonparametric frontier analysis," Economic Modelling, Elsevier, vol. 28(1-2), pages 515-525, January.
    56. Fatemi, Ali M. & Fooladi, Iraj & Garehkoolchian, Niloofar, 2017. "Gains from mergers and acquisitions in Japan," Global Finance Journal, Elsevier, vol. 32(C), pages 166-178.
    57. Ariff, Mohamed & Can, Luc, 2008. "Cost and profit efficiency of Chinese banks: A non-parametric analysis," China Economic Review, Elsevier, vol. 19(2), pages 260-273, June.
    58. Sherrill Shaffer, 2002. "Conduct in a Banking Monopoly," Review of Industrial Organization, Springer;The Industrial Organization Society, vol. 20(3), pages 221-238, May.
    59. Naceur, Sami Ben & Omran, Mohammed, 2011. "The effects of bank regulations, competition, and financial reforms on banks' performance," Emerging Markets Review, Elsevier, vol. 12(1), pages 1-20, March.
    60. Ali Ataullah & Tony Cockerill & Hang Le, 2004. "Financial liberalization and bank efficiency: a comparative analysis of India and Pakistan," Applied Economics, Taylor & Francis Journals, vol. 36(17), pages 1915-1924.
    61. Rangan, Nanda & Grabowski, Richard & Aly, Hassan Y. & Pasurka, Carl, 1988. "The technical efficiency of US banks," Economics Letters, Elsevier, vol. 28(2), pages 169-175.
    62. Lagoarde-Segot, Thomas & Lucey, Brian M., 2008. "Efficiency in emerging markets--Evidence from the MENA region," Journal of International Financial Markets, Institutions and Money, Elsevier, vol. 18(1), pages 94-105, February.
    63. Rolf Färe & Shawna Grosskopf, 2000. "Theory and Application of Directional Distance Functions," Journal of Productivity Analysis, Springer, vol. 13(2), pages 93-103, March.
    64. Stigler, George J, 1976. "The Xistence of X-Efficiency," American Economic Review, American Economic Association, vol. 66(1), pages 213-216, March.
    65. Kontolaimou, Alexandra & Tsekouras, Kostas, 2010. "Are cooperatives the weakest link in European banking? A non-parametric metafrontier approach," Journal of Banking & Finance, Elsevier, vol. 34(8), pages 1946-1957, August.
    66. Tan, Yong & Anchor, John, 2017. "The impacts of risk-taking behaviour and competition on technical efficiency: Evidence from the Chinese banking industry," Research in International Business and Finance, Elsevier, vol. 41(C), pages 90-104.
    67. Chambers, Robert G. & Chung, Yangho & Fare, Rolf, 1996. "Benefit and Distance Functions," Journal of Economic Theory, Elsevier, vol. 70(2), pages 407-419, August.
    Full references (including those not matched with items on IDEAS)

    Citations

    Citations are extracted by the CitEc Project, subscribe to its RSS feed for this item.
    as


    Cited by:

    1. Tharwah Shaalan, 2018. "Classification of Lending Risks and Interpretation of Operational Efficiency in Islamic Banks Registered on the Bahrain Stock Exchange," International Journal of Economics and Financial Issues, Econjournals, vol. 8(6), pages 151-156.

    Most related items

    These are the items that most often cite the same works as this one and are cited by the same works as this one.
    1. Bonasia, Mariangela & Kounetas, Konstantinos & Oreste, Napolitano, 2020. "Assessment of regional productive performance of European health systems under a metatechnology framework," Economic Modelling, Elsevier, vol. 84(C), pages 234-248.
    2. Kounetas, Konstantinos & Zervopoulos, Panagiotis D., 2019. "A cross-country evaluation of environmental performance: Is there a convergence-divergence pattern in technology gaps?," European Journal of Operational Research, Elsevier, vol. 273(3), pages 1136-1148.
    3. Napolitano, Oreste & Foresti, Pasquale & Kounetas, Konstantinos & Spagnolo, Nicola, 2023. "The impact of energy, renewable and CO2 emissions efficiency on countries’ productivity," Energy Economics, Elsevier, vol. 125(C).
    4. Areti Gkypali & Kostas Kounetas & Kostas Tsekouras, 2019. "European countries’ competitiveness and productive performance evolution: unraveling the complexity in a heterogeneity context," Journal of Evolutionary Economics, Springer, vol. 29(2), pages 665-695, April.
    5. Kounetas, Konstantinos & Stergiou, Eirini, 2019. "Technology heterogeneity in European industries' energy efficiency performance. The role of climate, greenhouse gases, path dependence and energy mix," MPRA Paper 92314, University Library of Munich, Germany.
    6. Kounetas, Kostas & Zervopoulos, Panagiotis, 2017. "Annex I and non-Annex I countries’productive performance revisited using a generalized directional distance function under a metafrontier framework: Is there any convergence-divergence pattern for tec," MPRA Paper 80904, University Library of Munich, Germany.
    7. Kontolaimou, Alexandra & Kounetas, Konstantinos & Mourtos, Ioannis & Tsekouras, Kostas, 2012. "Technology gaps in European banking: Put the blame on inputs or outputs?," Economic Modelling, Elsevier, vol. 29(5), pages 1798-1808.
    8. Kounetas, Kostas & Napolitano, Oreste & Stavropoulos, Spyridon & Burger, Martijn, 2018. "European Regional Productive Performance under a Metafrontier Framework. The role of patents and human capital on technology gap?," MPRA Paper 88957, University Library of Munich, Germany, revised 17 Jul 2018.
    9. Kounetas, Konstantinos, 2015. "Heterogeneous technologies, strategic groups and environmental efficiency technology gaps for European countries," Energy Policy, Elsevier, vol. 83(C), pages 277-287.
    10. El Moussawi, Chawki & Mansour, Rana, 2022. "Competition, cost efficiency and stability of banks in the MENA region," The Quarterly Review of Economics and Finance, Elsevier, vol. 84(C), pages 143-170.
    11. Chaffai, Mohamed & Coccorese, Paolo, 2019. "How far away is the MENA banking system? Efficiency comparisons with international banks," The North American Journal of Economics and Finance, Elsevier, vol. 49(C), pages 378-395.
    12. Emmanuel Tsiritakis, 2017. "Competition and Efficiency in EU Banking," SPOUDAI Journal of Economics and Business, SPOUDAI Journal of Economics and Business, University of Piraeus, vol. 67(2), pages 3-25, April-Jun.
    13. Economou, Polychronis & Malefaki, Sonia & Kounetas, Konstantinos, 2019. "Productive Performance and Technology Gaps using a Bayesian Metafrontier Production Function: A cross-country comparison," MPRA Paper 94462, University Library of Munich, Germany.
    14. Partovi, Elmira & Matousek, Roman, 2019. "Bank efficiency and non-performing loans: Evidence from Turkey," Research in International Business and Finance, Elsevier, vol. 48(C), pages 287-309.
    15. Kounetas, Konstantinos & Stergiou, Eirini, 2020. "European industrial eco-efficiency under different pollutants' scenarios and heterogeneity structures. Is there a definite direction?," MPRA Paper 98583, University Library of Munich, Germany.
    16. Johann Burgstaller, 2020. "Retail‐bank efficiency: Nonstandard goals and environmental determinants," Annals of Public and Cooperative Economics, Wiley Blackwell, vol. 91(2), pages 269-301, June.
    17. Lee, Chi-Chuan & Huang, Tai-Hsin, 2017. "Cost efficiency and technological gap in Western European banks: A stochastic metafrontier analysis," International Review of Economics & Finance, Elsevier, vol. 48(C), pages 161-178.
    18. Mercedes Beltrán-Esteve & José Gómez-Limón & Andrés Picazo-Tadeo & Ernest Reig-Martínez, 2014. "A metafrontier directional distance function approach to assessing eco-efficiency," Journal of Productivity Analysis, Springer, vol. 41(1), pages 69-83, February.
    19. Francesco Aiello & Graziella Bonanno, 2018. "On The Sources Of Heterogeneity In Banking Efficiency Literature," Journal of Economic Surveys, Wiley Blackwell, vol. 32(1), pages 194-225, February.
    20. Stephanie McWhinnie & Kofi Otumawu-Apreku, 2013. "Profit Efficiency of the South Australian Rock Lobster Fishery: Nerlovian and Directional Distance Function Approach," School of Economics and Public Policy Working Papers 2013-13, University of Adelaide, School of Economics and Public Policy.

    More about this item

    Keywords

    Risk efficiency; Middle East banks; Directional distance function; Metatechnology;
    All these keywords.

    JEL classification:

    • D20 - Microeconomics - - Production and Organizations - - - General
    • D24 - Microeconomics - - Production and Organizations - - - Production; Cost; Capital; Capital, Total Factor, and Multifactor Productivity; Capacity
    • G1 - Financial Economics - - General Financial Markets
    • G2 - Financial Economics - - Financial Institutions and Services
    • G21 - Financial Economics - - Financial Institutions and Services - - - Banks; Other Depository Institutions; Micro Finance Institutions; Mortgages

    Statistics

    Access and download statistics

    Corrections

    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:eee:glofin:v:46:y:2020:i:c:s1044028318302977. See general information about how to correct material in RePEc.

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    If CitEc recognized a bibliographic reference but did not link an item in RePEc to it, you can help with this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: Catherine Liu (email available below). General contact details of provider: http://www.elsevier.com/locate/inca/620162 .

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service. RePEc uses bibliographic data supplied by the respective publishers.