Distribution-free tests of stochastic monotonicity
Author
Abstract
Suggested Citation
DOI: 10.1016/j.jeconom.2012.02.005
Download full text from publisher
As the access to this document is restricted, you may want to search for a different version of it.
References listed on IDEAS
- Jacob Boudoukh & Matthew Richardson & Tom Smith & Robert F. Whitelaw, 1999. "Ex Ante Bond Returns and the Liquidity Preference Hypothesis," Journal of Finance, American Finance Association, vol. 54(3), pages 1153-1167, June.
- Banerjee, Moulinath & Mukherjee, Debasri & Mishra, Santosh, 2009. "Semiparametric binary regression models under shape constraints with an application to Indian schooling data," Journal of Econometrics, Elsevier, vol. 149(2), pages 101-117, April.
- Arthur Lewbel & Oliver Linton, 2007.
"Nonparametric Matching and Efficient Estimators of Homothetically Separable Functions,"
Econometrica, Econometric Society, vol. 75(4), pages 1209-1227, July.
- Arthur Lewbel & Oliver Linton, 2003. "Nonparametric Matching and Efficient Estimators of Homothetically Separable Functions," Boston College Working Papers in Economics 585, Boston College Department of Economics, revised 04 Sep 2006.
- Aguirregabiria, Victor, 2010. "Another Look at the Identification of Dynamic Discrete Decision Processes: An Application to Retirement Behavior," Journal of Business & Economic Statistics, American Statistical Association, vol. 28(2), pages 201-218.
- Sokbae Lee & Oliver Linton & Yoon-Jae Whang, 2009.
"Testing for Stochastic Monotonicity,"
Econometrica, Econometric Society, vol. 77(2), pages 585-602, March.
- Lee, Sokbae & Linton, Oliver & Whang, Yoon-Jae, 2006. "Testing for stochastic monotonicity," LSE Research Online Documents on Economics 4425, London School of Economics and Political Science, LSE Library.
- Sokbae Lee & Oliver Linton & Yoon-Jae Whang, 2006. "Testing For Stochasticmonotonicity," STICERD - Econometrics Paper Series 504, Suntory and Toyota International Centres for Economics and Related Disciplines, LSE.
- Sokbae (Simon) Lee & Oliver Linton & Yoon-Jae Whang, 2008. "Testing for stochastic monotonicity," CeMMAP working papers CWP21/08, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Valentino Dardanoni & Mario Fiorini & Antonio Forcina, 2012.
"Stochastic monotonicity in intergenerational mobility tables,"
Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 27(1), pages 85-107, January.
- Valentino Dardanoni & Mario Fiorini & Antonio Forcina, 2008. "Stochastic Monotonicity in Intergenerational Mobility Tables," Working Paper Series 156, Finance Discipline Group, UTS Business School, University of Technology, Sydney.
- Escanciano, Juan Carlos & Jacho-Chávez, David T., 2012. "n-uniformly consistent density estimation in nonparametric regression models," Journal of Econometrics, Elsevier, vol. 167(2), pages 305-316.
- Durot, Cécile, 2003. "A Kolmogorov-type test for monotonicity of regression," Statistics & Probability Letters, Elsevier, vol. 63(4), pages 425-433, July.
- Richard Ericson & Ariel Pakes, 1995. "Markov-Perfect Industry Dynamics: A Framework for Empirical Work," The Review of Economic Studies, Review of Economic Studies Ltd, vol. 62(1), pages 53-82.
- Pakes, Ariel S, 1986.
"Patents as Options: Some Estimates of the Value of Holding European Patent Stocks,"
Econometrica, Econometric Society, vol. 54(4), pages 755-784, July.
- Ariel Pakes, 1984. "Patents as Options: Some Estimates of the Value of Holding European Patent Stocks," NBER Working Papers 1340, National Bureau of Economic Research, Inc.
- Charles F. Manski & John V. Pepper, 2000.
"Monotone Instrumental Variables, with an Application to the Returns to Schooling,"
Econometrica, Econometric Society, vol. 68(4), pages 997-1012, July.
- Charles F. Manski & John V. Pepper, 1998. "Monotone Instrumental Variables with an Application to the Returns to Schooling," NBER Technical Working Papers 0224, National Bureau of Economic Research, Inc.
- Charles F. Manski & John V. Pepper, 1998. "Monotone Instrumental Variables: With an Application to the Returns to Schooling," Virginia Economics Online Papers 308, University of Virginia, Department of Economics.
- Olley, G Steven & Pakes, Ariel, 1996.
"The Dynamics of Productivity in the Telecommunications Equipment Industry,"
Econometrica, Econometric Society, vol. 64(6), pages 1263-1297, November.
- G. Steven Olley & Ariel Pakes, 1992. "The Dynamics of Productivity in the Telecommunications Equipment Industry," NBER Working Papers 3977, National Bureau of Economic Research, Inc.
- George S Olley & Ariel Pakes, 1992. "The Dynamics Of Productivity In The Telecommunications Equipment Industry," Working Papers 92-2, Center for Economic Studies, U.S. Census Bureau.
- Paul R. Milgrom, 1981.
"Good News and Bad News: Representation Theorems and Applications,"
Bell Journal of Economics, The RAND Corporation, vol. 12(2), pages 380-391, Autumn.
- Paul R. Milgrom, 1979. "Good Nevs and Bad News: Representation Theorems and Applications," Discussion Papers 407R, Northwestern University, Center for Mathematical Studies in Economics and Management Science.
- Gordon Bril & Richard Dykstra & Carolyn Pillers & Tim Robertson, 1984. "Isotonic Regression in Two Independent Variables," Journal of the Royal Statistical Society Series C, Royal Statistical Society, vol. 33(3), pages 352-357, November.
- Matthew Richardson & Paul Richardson & Tom Smith, "undated". "The Monotonicity of the Term Premium: Another Look (Reprint 026)," Rodney L. White Center for Financial Research Working Papers 3-92, Wharton School Rodney L. White Center for Financial Research.
- Matthew Richardson & Paul Richardson & Tom Smith, "undated". "The Monotonicity of the Term Premium: Another Look (Reprint 026)," Rodney L. White Center for Financial Research Working Papers 03-92, Wharton School Rodney L. White Center for Financial Research.
- G. W. Cran, 1980. "Amalgamation of Means in the Case of Simple Ordering," Journal of the Royal Statistical Society Series C, Royal Statistical Society, vol. 29(2), pages 209-211, June.
- Richardson, Matthew & Richardson, Paul & Smith, Tom, 1992. "The monotonicity of the term premium *1: Another look," Journal of Financial Economics, Elsevier, vol. 31(1), pages 97-105.
- George Akerlof, 1976. "The Economics of Caste and of the Rat Race and Other Woeful Tales," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 90(4), pages 599-617.
- George A. Akerlof, 1970. "The Market for "Lemons": Quality Uncertainty and the Market Mechanism," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 84(3), pages 488-500.
- Michael Spence, 1973. "Job Market Signaling," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 87(3), pages 355-374.
Citations
Citations are extracted by the CitEc Project, subscribe to its RSS feed for this item.
Cited by:
- Ismaël Mourifié & Marc Henry & Romuald Méango, 2020.
"Sharp Bounds and Testability of a Roy Model of STEM Major Choices,"
Journal of Political Economy, University of Chicago Press, vol. 128(8), pages 3220-3283.
- Ismael Mourifie & Marc Henry & Romuald Meango, 2017. "Sharp bounds and testability of a Roy model of STEM major choices," Papers 1709.09284, arXiv.org, revised Nov 2019.
- Ismael Mourifié & Marc Henry & Romuald Méango, 2018. "Sharp Bounds and Testability of a Roy Model of STEM Major Choices," Working Papers 2018-084, Human Capital and Economic Opportunity Working Group.
- Ismael Mourifie & Marc Henry & Romuald Meango, 2018. "Sharp Bounds And Testability Of A Roy Model Of Stem Major Choices," Working Papers tecipa-624, University of Toronto, Department of Economics.
- Matthew A. Masten & Alexandre Poirier, 2018. "Interpreting Quantile Independence," Papers 1804.10957, arXiv.org.
- Lee, Sokbae & Song, Kyungchul & Whang, Yoon-Jae, 2018.
"Testing For A General Class Of Functional Inequalities,"
Econometric Theory, Cambridge University Press, vol. 34(5), pages 1018-1064, October.
- Sokbae Lee & Kyungchul Song & Yoon-Jae Whang, 2014. "Testing For A General Class Of Functional Inequalities," KIER Working Papers 889, Kyoto University, Institute of Economic Research.
- Sokbae (Simon) Lee & Kyungchui (Kevin) Song & Yoon-Jae Whang, 2014. "Testing for a general class of functional inequalities," CeMMAP working papers CWP09/14, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Sokbae (Simon) Lee & Kyungchui (Kevin) Song & Yoon-Jae Whang, 2014. "Testing for a general class of functional inequalities," CeMMAP working papers 09/14, Institute for Fiscal Studies.
- Hoderlein, Stefan & Su, Liangjun & White, Halbert & Yang, Thomas Tao, 2016.
"Testing for monotonicity in unobservables under unconfoundedness,"
Journal of Econometrics, Elsevier, vol. 193(1), pages 183-202.
- Stefan Hoderlein & Liangjun Su & Halbert White & Thomas Tao Yang, 2015. "Testing for Monotonicity in Unobservables under Unconfoundedness," Boston College Working Papers in Economics 899, Boston College Department of Economics.
- Lee, Tae-Hwy & Tu, Yundong & Ullah, Aman, 2014.
"Nonparametric and semiparametric regressions subject to monotonicity constraints: Estimation and forecasting,"
Journal of Econometrics, Elsevier, vol. 182(1), pages 196-210.
- Tae-Hwy Lee & Yundong Tu & Aman Ullah, 2014. "Nonparametric and Semiparametric Regressions Subject to Monotonicity Constraints: Estimation and Forecasting," Working Papers 201404, University of California at Riverside, Department of Economics.
- Gutknecht, Daniel, 2016. "Testing for monotonicity under endogeneity," Journal of Econometrics, Elsevier, vol. 190(1), pages 100-114.
- Henry, Marc & Méango, Romuald & Mourifié, Ismaël, 2024. "Role models and revealed gender-specific costs of STEM in an extended Roy model of major choice," Journal of Econometrics, Elsevier, vol. 238(2).
- Denis Chetverikov & Daniel Wilhelm, 2016. "Nonparametric instrumental variable estimation under monotonicity," CeMMAP working papers 48/16, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm, 2017.
"Nonparametric Instrumental Variable Estimation Under Monotonicity,"
Econometrica, Econometric Society, vol. 85, pages 1303-1320, July.
- Denis Chetverikov & Daniel Wilhelm, 2015. "Nonparametric instrumental variable estimation under monotonicity," CeMMAP working papers CWP39/15, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm, 2017. "Nonparametric instrumental variable estimation under monotonicity," CeMMAP working papers CWP14/17, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm, 2016. "Nonparametric instrumental variable estimation under monotonicity," CeMMAP working papers CWP48/16, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm, 2015. "Nonparametric instrumental variable estimation under monotonicity," Papers 1507.05270, arXiv.org.
- Chetverikov, Denis & Wilhelm, Daniel & Kim, Dongwoo, 2021.
"An Adaptive Test Of Stochastic Monotonicity,"
Econometric Theory, Cambridge University Press, vol. 37(3), pages 495-536, June.
- Denis Chetverikov & Daniel Wilhelm & Dongwoo Kim, 2018. "An adaptive test of stochastic monotonicity," CeMMAP working papers CWP24/18, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm & Dongwoo Kim, 2020. "An Adaptive Test of Stochastic Monotonicity," CeMMAP working papers CWP17/20, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm & Dongwoo Kim, 2019. "An adaptive test of stochastic monotonicity," CeMMAP working papers CWP49/19, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Beare, Brendan K. & Shi, Xiaoxia, 2019.
"An improved bootstrap test of density ratio ordering,"
Econometrics and Statistics, Elsevier, vol. 10(C), pages 9-26.
- beare, brendan & shi, xiaoxia, 2015. "An improved bootstrap test of density ratio ordering," MPRA Paper 74772, University Library of Munich, Germany.
- José Romeo & Nelson Tanaka & Antonio Pedroso-de-Lima & Victor Salinas-Torres, 2013. "Large sample properties for a class of copulas in bivariate survival analysis," Metrika: International Journal for Theoretical and Applied Statistics, Springer, vol. 76(8), pages 997-1015, November.
- Lee, Sokbae & Song, Kyungchul & Whang, Yoon-Jae, 2013.
"Testing functional inequalities,"
Journal of Econometrics, Elsevier, vol. 172(1), pages 14-32.
- Sokbae (Simon) Lee & Kyungchui (Kevin) Song & Yoon-Jae Whang, 2011. "Testing functional inequalities," CeMMAP working papers CWP12/11, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Zheng Fang, 2021. "A Unifying Framework for Testing Shape Restrictions," Papers 2107.12494, arXiv.org, revised Aug 2021.
- Liu, Nianqing & Vuong, Quang & Xu, Haiqing, 2017. "Rationalization and identification of binary games with correlated types," Journal of Econometrics, Elsevier, vol. 201(2), pages 249-268.
- Daniel Gutknecht, 2013. "Testing for Monotonicity under Endogeneity An Application to the Reservation Wage Function," Economics Series Working Papers 673, University of Oxford, Department of Economics.
- repec:cte:werepe:we1138 is not listed on IDEAS
- Berghaus, Betina & Bücher, Axel, 2014. "Nonparametric tests for tail monotonicity," Journal of Econometrics, Elsevier, vol. 180(2), pages 117-126.
- repec:wrk:warwec:991 is not listed on IDEAS
- Denis Chetverikov & Daniel Wilhelm, 2015. "Nonparametric instrumental variable estimation under monotonicity," CeMMAP working papers 39/15, Institute for Fiscal Studies.
- Gutknecht, Daniel, 2012. "Do Reservation Wages Decline Monotonically? A Novel Statistical Test," Economic Research Papers 270635, University of Warwick - Department of Economics.
- Colubi, Ana & Domínguez-Menchero, J. Santos & González-Rodríguez, Gil, 2014. "Testing constancy in monotone response models," Computational Statistics & Data Analysis, Elsevier, vol. 72(C), pages 45-56.
- Toru Kitagawa & Martin Nybom & Jan Stuhler, 2018. "Measurement error and rank correlations," CeMMAP working papers CWP28/18, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Seo, Juwon, 2018. "Tests of stochastic monotonicity with improved power," Journal of Econometrics, Elsevier, vol. 207(1), pages 53-70.
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.- Chetverikov, Denis & Wilhelm, Daniel & Kim, Dongwoo, 2021.
"An Adaptive Test Of Stochastic Monotonicity,"
Econometric Theory, Cambridge University Press, vol. 37(3), pages 495-536, June.
- Denis Chetverikov & Daniel Wilhelm & Dongwoo Kim, 2018. "An adaptive test of stochastic monotonicity," CeMMAP working papers CWP24/18, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm & Dongwoo Kim, 2020. "An Adaptive Test of Stochastic Monotonicity," CeMMAP working papers CWP17/20, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Denis Chetverikov & Daniel Wilhelm & Dongwoo Kim, 2019. "An adaptive test of stochastic monotonicity," CeMMAP working papers CWP49/19, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Le-Yu Chen & Jerzy Szroeter, 2009.
"Hypothesis testing of multiple inequalities: the method of constraint chaining,"
CeMMAP working papers
CWP13/09, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Le-Yu Chen & Jerzy Szroeter, 2009. "Hypothesis testing of multiple inequalities: the method of constraint chaining," CeMMAP working papers 13/09, Institute for Fiscal Studies.
- Sokbae Lee & Oliver Linton & Yoon-Jae Whang, 2009.
"Testing for Stochastic Monotonicity,"
Econometrica, Econometric Society, vol. 77(2), pages 585-602, March.
- Lee, Sokbae & Linton, Oliver & Whang, Yoon-Jae, 2006. "Testing for stochastic monotonicity," LSE Research Online Documents on Economics 4425, London School of Economics and Political Science, LSE Library.
- Sokbae Lee & Oliver Linton & Yoon-Jae Whang, 2006. "Testing For Stochasticmonotonicity," STICERD - Econometrics Paper Series 504, Suntory and Toyota International Centres for Economics and Related Disciplines, LSE.
- Sokbae (Simon) Lee & Oliver Linton & Yoon-Jae Whang, 2008. "Testing for stochastic monotonicity," CeMMAP working papers CWP21/08, Centre for Microdata Methods and Practice, Institute for Fiscal Studies.
- Panagiotis T. Konstantinou, 2005. "The Expectations Hypothesis of the Term Structure : A Look at the Polish Interbank Market," Emerging Markets Finance and Trade, Taylor & Francis Journals, vol. 41(3), pages 70-91, May.
- Ornelas, Jose Renato Haas & Silva Jr., Antonio Francisco de Almeida, 2015.
"Testing the liquidity preference hypothesis using survey forecasts,"
Emerging Markets Review, Elsevier, vol. 23(C), pages 173-185.
- Jose Renato Haas Ornelas & Antonio Francisco de Almeida Silva Jr, 2014. "Testing the Liquidity Preference Hypothesis using Survey Forecasts," Working Papers Series 353, Central Bank of Brazil, Research Department.
- Patton, Andrew J. & Timmermann, Allan, 2010. "Monotonicity in asset returns: New tests with applications to the term structure, the CAPM, and portfolio sorts," Journal of Financial Economics, Elsevier, vol. 98(3), pages 605-625, December.
- Konstantinou, Panagiotis, 2004. "Term Structure Dynamics: A Daily View from the Hungarian Foreign Currency Deposits Markets," Economia Internazionale / International Economics, Camera di Commercio Industria Artigianato Agricoltura di Genova, vol. 57(3), pages 315-331.
- Drakos, Konstantinos, 2001. "Fixed income excess returns and time to maturity," International Review of Financial Analysis, Elsevier, vol. 10(4), pages 431-442.
- Berghaus, Betina & Bücher, Axel, 2014. "Nonparametric tests for tail monotonicity," Journal of Econometrics, Elsevier, vol. 180(2), pages 117-126.
- Ostdiek, Barbara, 1998. "The world ex ante risk premium: an empirical investigation," Journal of International Money and Finance, Elsevier, vol. 17(6), pages 967-999, December.
- Hooker, Mark A., 1999. "The maturity structure of term premia with time-varying expected returns," The Quarterly Review of Economics and Finance, Elsevier, vol. 39(3), pages 391-407.
- Tzavalis, Elias & Wickens, Michael R, 1997. "Explaining the Failures of the Term Spread Models of the Rational Expectations Hypothesis of the Term Structure," Journal of Money, Credit and Banking, Blackwell Publishing, vol. 29(3), pages 364-380, August.
- Nuria Rodriguez-Planas, 2003.
"Signaling in The Labor Market: New Evidence On Layoffs, and Plant Closings,"
William Davidson Institute Working Papers Series
2003-610, William Davidson Institute at the University of Michigan.
- Rodríguez-Planas, Núria, 2004. "Signaling in the Labor Market: New Evidence on Layoffs and Plant Closings," IZA Discussion Papers 1009, Institute of Labor Economics (IZA).
- repec:eee:labchp:v:2:y:1986:i:c:p:789-848 is not listed on IDEAS
- Klaus Friesenbichler & George Clarke & Michael Wong, 2014. "Price competition and market transparency: evidence from a random response technique," Empirica, Springer;Austrian Institute for Economic Research;Austrian Economic Association, vol. 41(1), pages 5-21, February.
- Victor Aguirregabiria & Margaret Slade, 2017.
"Empirical models of firms and industries,"
Canadian Journal of Economics/Revue canadienne d'économique, John Wiley & Sons, vol. 50(5), pages 1445-1488, December.
- Victor Aguirregabiria & Margaret Slade, 2017. "Empirical models of firms and industries," Canadian Journal of Economics, Canadian Economics Association, vol. 50(5), pages 1445-1488, December.
- Aguirregabiria, Victor & Slade, Margaret, 2017. "Empirical Models of Firms and Industries," CEPR Discussion Papers 12074, C.E.P.R. Discussion Papers.
- Aguirregabiria, Victor & Slade, Margaret E., 2017. "Empirical Models of Firms and Industries," Microeconomics.ca working papers margaret_e._slade-2017-4, Vancouver School of Economics, revised 27 Apr 2017.
- Victor Aguirregabiria & Margaret Slade, 2017. "Empirical Models of Firms and Industries," Working Papers tecipa-580, University of Toronto, Department of Economics.
- Robin S. Lee, 2013.
"Vertical Integration and Exclusivity in Platform and Two-Sided Markets,"
American Economic Review, American Economic Association, vol. 103(7), pages 2960-3000, December.
- Robin S. Lee, 2007. "Vertical Integration and Exclusivity in Two-Sided Markets," Working Papers 07-39, NET Institute, revised Aug 2012.
- Mano, Yukichi & 真野, 裕吉 & Suzuki, Aya & 鈴木, 綾, 2013. "Measuring Agglomeration Economies: The Case of the Ethiopian Cut Flower Industry," Discussion Papers 2013-04, Graduate School of Economics, Hitotsubashi University.
- Xin Jin, 2014. "The Signaling Role of Not Being Promoted: Theory and Evidence," Working Papers 0314, University of South Florida, Department of Economics.
- Coublucq, Daniel, 2013. "Demand estimation with selection bias: A dynamic game approach with an application to the US railroad industry," DICE Discussion Papers 94, Heinrich Heine University Düsseldorf, Düsseldorf Institute for Competition Economics (DICE).
- Matthew A. Masten & Alexandre Poirier, 2018. "Interpreting Quantile Independence," Papers 1804.10957, arXiv.org.
More about this item
Keywords
Stochastic monotonicity; Conditional moments; Least concave majorant; Copula process; Distribution-free in finite samples; Tests invariant to monotone transforms;All these keywords.
JEL classification:
- C14 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Semiparametric and Nonparametric Methods: General
- C15 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Statistical Simulation Methods: General
Statistics
Access and download statisticsCorrections
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:econom:v:170:y:2012:i:1:p:68-75. 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/jeconom .
Please note that corrections may take a couple of weeks to filter through the various RePEc services.