IDEAS home Printed from https://ideas.repec.org/p/bdi/wptemi/td_985_14.html
   My bibliography  Save this paper

Dif-in-dif estimators of multiplicative treatment effects

Author

Listed:
  • Emanuele Ciani

    (Bank of Italy)

  • Paul Fisher

    (Institute for Social and Economic Research, University of Essex, UK)

Abstract

We consider a difference-in-differences setting with a continuous outcome, such as wages or expenditure. The standard practice is to take the logarithm of the outcome and then interpret the results as an approximation of the multiplicative treatment effect on the original outcome. We argue that a researcher should instead focus on the original outcome when discussing causal inference. Furthermore, it is preferable to use a non-linear estimator, because running OLS on the log-linearised model might confound distributional and mean changes. We illustrate the argument with an original empirical analysis of the impact of the UK Educational Maintenance Allowance on households' expenditure, and with a simulation exercise.

Suggested Citation

  • Emanuele Ciani & Paul Fisher, 2014. "Dif-in-dif estimators of multiplicative treatment effects," Temi di discussione (Economic working papers) 985, Bank of Italy, Economic Research and International Relations Area.
  • Handle: RePEc:bdi:wptemi:td_985_14
    as

    Download full text from publisher

    File URL: http://www.bancaditalia.it/pubblicazioni/temi-discussione/2014/2014-0985/en_tema_985.pdf
    Download Restriction: no
    ---><---

    Other versions of this item:

    References listed on IDEAS

    as
    1. John J. Donohue III & Steven D. Levitt, 2008. "Measurement Error, Legalized Abortion, and the Decline in Crime: A Response to Foote and Goetz," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 123(1), pages 425-440.
    2. Eric A. Verhoogen, 2008. "Trade, Quality Upgrading, and Wage Inequality in the Mexican Manufacturing Sector," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 123(2), pages 489-530.
    3. Nathan Nunn & Nancy Qian, 2011. "The Potato's Contribution to Population and Urbanization: Evidence From A Historical Experiment," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 126(2), pages 593-650.
    4. John J. Donohue III & Steven D. Levitt, 2001. "The Impact of Legalized Abortion on Crime," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 116(2), pages 379-420.
    5. Duflo, Esther & Glennerster, Rachel & Kremer, Michael, 2008. "Using Randomization in Development Economics Research: A Toolkit," Handbook of Development Economics, in: T. Paul Schultz & John A. Strauss (ed.), Handbook of Development Economics, edition 1, volume 4, chapter 61, pages 3895-3962, Elsevier.
    6. J.M.C. Santos Silva & Silvana Tenreyro, 2010. "Currency Unions in Prospect and Retrospect," Annual Review of Economics, Annual Reviews, vol. 2(1), pages 51-74, September.
    7. Manning, Willard G., 1998. "The logged dependent variable, heteroscedasticity, and the retransformation problem," Journal of Health Economics, Elsevier, vol. 17(3), pages 283-295, June.
    8. Lorraine Dearden & Carl Emmerson & Costas Meghir, 2009. "Conditional Cash Transfers and School Dropout Rates," Journal of Human Resources, University of Wisconsin Press, vol. 44(4).
    9. Richard Hornbeck, 2010. "Barbed Wire: Property Rights and Agricultural Development," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 125(2), pages 767-810.
    10. Mullahy, John, 1998. "Much ado about two: reconsidering retransformation and the two-part model in health econometrics," Journal of Health Economics, Elsevier, vol. 17(3), pages 247-281, June.
    11. Alberto Abadie, 2005. "Semiparametric Difference-in-Differences Estimators," The Review of Economic Studies, Review of Economic Studies Ltd, vol. 72(1), pages 1-19.
    12. Blackburn, McKinley L., 2007. "Estimating wage differentials without logarithms," Labour Economics, Elsevier, vol. 14(1), pages 73-98, January.
    13. Oriana Bandiera & Iwan Barankay & Imran Rasul, 2007. "Incentives for Managers and Inequality among Workers: Evidence from a Firm-Level Experiment," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 122(2), pages 729-773.
    14. John Mullahy, 1998. "Much Ado About Two: Reconsidering Retransformation and the Two-Part Model in Health Economics," NBER Technical Working Papers 0228, National Bureau of Economic Research, Inc.
    15. Harrison Hong & Marcin Kacperczyk, 2010. "Competition and Bias," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 125(4), pages 1683-1725.
    16. Jonathan Gruber & Daniel M. Hungerman, 2008. "The Church Versus the Mall: What Happens When Religion Faces Increased Secular Competition?," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 123(2), pages 831-862.
    17. Stefano DellaVigna & Ethan Kaplan, 2007. "The Fox News Effect: Media Bias and Voting," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 122(3), pages 1187-1234.
    18. Blundell, Richard & Macurdy, Thomas, 1999. "Labor supply: A review of alternative approaches," Handbook of Labor Economics, in: O. Ashenfelter & D. Card (ed.), Handbook of Labor Economics, edition 1, volume 3, chapter 27, pages 1559-1695, Elsevier.
    19. Erich Battistin & Richard Blundell & Arthur Lewbel, 2009. "Why Is Consumption More Log Normal than Income? Gibrat's Law Revisited," Journal of Political Economy, University of Chicago Press, vol. 117(6), pages 1140-1154, December.
    20. Chunrong Ai & Edward C. Norton, 2008. "A semiparametric derivative estimator in log transformation models," Econometrics Journal, Royal Economic Society, vol. 11(3), pages 538-553, November.
    21. Gregg, Paul & Waldfogel, Jane & Washbrook, Elizabeth, 2006. "Family expenditures post-welfare reform in the UK: Are low-income families starting to catch up?," Labour Economics, Elsevier, vol. 13(6), pages 721-746, December.
    22. Robert Jensen & Emily Oster, 2009. "The Power of TV: Cable Television and Women's Status in India," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 124(3), pages 1057-1094.
    23. Puhani, Patrick A., 2012. "The treatment effect, the cross difference, and the interaction term in nonlinear “difference-in-differences” models," Economics Letters, Elsevier, vol. 115(1), pages 85-87.
    24. Jeremiah E. Dittmar, 2011. "Information Technology and Economic Change: The Impact of The Printing Press," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 126(3), pages 1133-1172.
    25. Angrist, Joshua D, 2001. "Estimations of Limited Dependent Variable Models with Dummy Endogenous Regressors: Simple Strategies for Empirical Practice," Journal of Business & Economic Statistics, American Statistical Association, vol. 19(1), pages 2-16, January.
    26. Seema Jayachandran & Adriana Lleras-Muney, 2009. "Life Expectancy and Human Capital Investments: Evidence from Maternal Mortality Declines," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 124(1), pages 349-397.
    27. Maarten L. Buis, 2010. "Stata tip 87: Interpretation of interactions in nonlinear models," Stata Journal, StataCorp LP, vol. 10(2), pages 305-308, June.
    28. J. M. C. Santos Silva & Silvana Tenreyro, 2006. "The Log of Gravity," The Review of Economics and Statistics, MIT Press, vol. 88(4), pages 641-658, November.
    29. David H. Autor, 2001. "Why Do Temporary Help Firms Provide Free General Skills Training?," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 116(4), pages 1409-1448.
    30. DiNardo, John & Lee, David S., 2011. "Program Evaluation and Research Designs," Handbook of Labor Economics, in: O. Ashenfelter & D. Card (ed.), Handbook of Labor Economics, edition 1, volume 4, chapter 5, pages 463-536, Elsevier.
    31. Emma Aguila & Orazio Attanasio & Costas Meghir, 2011. "Changes in Consumption at Retirement: Evidence from Panel Data," The Review of Economics and Statistics, MIT Press, vol. 93(3), pages 1094-1099, August.
    32. John Mullahy, 1997. "Instrumental-Variable Estimation Of Count Data Models: Applications To Models Of Cigarette Smoking Behavior," The Review of Economics and Statistics, MIT Press, vol. 79(4), pages 586-593, November.
    33. Wooldridge, Jeffrey M, 1992. "Some Alternatives to the Box-Cox Regression Model," International Economic Review, Department of Economics, University of Pennsylvania and Osaka University Institute of Social and Economic Research Association, vol. 33(4), pages 935-955, November.
    34. Martina Björkman & Jakob Svensson, 2009. "Power to the People: Evidence from a Randomized Field Experiment on Community-Based Monitoring in Uganda," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 124(2), pages 735-769.
    35. Susan Athey & Guido W. Imbens, 2006. "Identification and Inference in Nonlinear Difference-in-Differences Models," Econometrica, Econometric Society, vol. 74(2), pages 431-497, March.
    36. Ai, Chunrong & Norton, Edward C., 2003. "Interaction terms in logit and probit models," Economics Letters, Elsevier, vol. 80(1), pages 123-129, July.
    37. Jeffrey M. Wooldridge, 2003. "Cluster-Sample Methods in Applied Econometrics," American Economic Review, American Economic Association, vol. 93(2), pages 133-138, May.
    38. Donald P. Morgan & Bertrand Rime & Philip E. Strahan, 2004. "Bank Integration and State Business Cycles," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 119(4), pages 1555-1584.
    39. Donald Morgan & Bertrand Rime & Philip Strahan, 2003. "Bank Integration and State Business Cycles," NBER Working Papers 9704, National Bureau of Economic Research, Inc.
    40. Stephen G. Donald & Kevin Lang, 2007. "Inference with Difference-in-Differences and Other Panel Data," The Review of Economics and Statistics, MIT Press, vol. 89(2), pages 221-233, May.
    41. Joshua D. Angrist & Jörn-Steffen Pischke, 2009. "Mostly Harmless Econometrics: An Empiricist's Companion," Economics Books, Princeton University Press, edition 1, number 8769.
    42. Amy Finkelstein, 2004. "Static and Dynamic Effects of Health Policy: Evidence from the Vaccine Industry," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 119(2), pages 527-564.
    43. Hoyt Bleakley, 2007. "Disease and Development: Evidence from Hookworm Eradication in the American South," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 122(1), pages 73-117.
    44. Betsey Stevenson & Justin Wolfers, 2006. "Bargaining in the Shadow of the Law: Divorce Laws and Family Distress," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 121(1), pages 267-288.
    45. Marianne Bertrand & Esther Duflo & Sendhil Mullainathan, 2004. "How Much Should We Trust Differences-In-Differences Estimates?," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 119(1), pages 249-275.
    46. Meyer, Bruce D, 1995. "Natural and Quasi-experiments in Economics," Journal of Business & Economic Statistics, American Statistical Association, vol. 13(2), pages 151-161, April.
    47. Martha J. Bailey, 2006. "More Power to the Pill: The Impact of Contraceptive Freedom on Women's Life Cycle Labor Supply," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 121(1), pages 289-320.
    48. John J. Donohue III & James J. Heckman & Petra E. Todd, 2002. "The Schooling of Southern Blacks: The Roles of Legal Activism and Private Philanthropy, 1910–1960," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 117(1), pages 225-268.
    49. Erica Field, 2007. "Entitled to Work: Urban Property Rights and Labor Supply in Peru," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 122(4), pages 1561-1602.
    50. Christopher L. Foote & Christopher F. Goetz, 2008. "The Impact of Legalized Abortion on Crime: Comment," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 123(1), pages 407-423.
    51. Angrist, Joshua D, 2001. "Estimations of Limited Dependent Variable Models with Dummy Endogenous Regressors: Simple Strategies for Empirical Practice: Reply," Journal of Business & Economic Statistics, American Statistical Association, vol. 19(1), pages 27-28, January.
    52. Asim Ijaz Khwaja & Atif Mian, 2005. "Do Lenders Favor Politically Connected Firms? Rent Provision in an Emerging Financial Market," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 120(4), pages 1371-1411.
    53. Manning, Willard G. & Mullahy, John, 2001. "Estimating log models: to transform or not to transform?," Journal of Health Economics, Elsevier, vol. 20(4), pages 461-494, July.
    54. Amy Finkelstein, 2007. "The Aggregate Effects of Health Insurance: Evidence from the Introduction of Medicare," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 122(1), pages 1-37.
    55. John Mullahy, 1999. "Interaction Effects and Difference-in-Difference Estimation in Loglinear Models," NBER Technical Working Papers 0245, National Bureau of Economic Research, Inc.
    56. M. L. Blackburn, 2010. "The Impact of Internal Migration on Married Couples' Earnings in Britain," Economica, London School of Economics and Political Science, vol. 77(307), pages 584-603, July.
    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. Broten, Nicholas & Dworsky, Michael & Powell, David, 2022. "Do temporary workers experience additional employment and earnings risk after workplace injuries?," Journal of Public Economics, Elsevier, vol. 209(C).
    2. Alex Hollingsworth & Krzysztof Karbownik & Melissa A. Thomasson & Anthony Wray, 2024. "The Gift of a Lifetime: The Hospital, Modern Medicine, and Mortality," American Economic Review, American Economic Association, vol. 114(7), pages 2201-2238, July.
    3. Emanuele Ciani & Guido de Blasio, 2015. "European structural funds during the crisis: evidence from Southern Italy," IZA Journal of Labor Policy, Springer;Forschungsinstitut zur Zukunft der Arbeit GmbH (IZA), vol. 4(1), pages 1-31, December.
    4. Kastoryano, Stephen & Vollaard, Ben, 2022. "Nautical Patrol and Illegal Fishing Practices," Discussion Paper 2022-016, Tilburg University, Center for Economic Research.
    5. Arslan Aziz & Hui Li & Rahul Telang, 2023. "The Consequences of Rating Inflation on Platforms: Evidence from a Quasi-Experiment," Information Systems Research, INFORMS, vol. 34(2), pages 590-608, June.
    6. Ivus, Olena & Park, Walter, 2019. "Patent reforms and exporter behaviour: Firm-level evidence from developing countries," Journal of the Japanese and International Economies, Elsevier, vol. 51(C), pages 129-147.
    7. Gabriela Galassi, 2021. "Labor Demand Response to Labor Supply Incentives: Lessons from the German Mini-Job Reform," Staff Working Papers 21-15, Bank of Canada.
    8. Jose J. Canals-Cerda & Brian Jonghwan Lee, 2021. "COVID-19 and Auto Loan Origination Trends," Working Papers 21-28, Federal Reserve Bank of Philadelphia.
    9. Simone Balestra & Helge Liebert & Nicole Maestas & Tisamarie B. Sherry, 2021. "Behavioral Responses to Supply-Side Drug Policy During the Opioid Epidemic," NBER Working Papers 29596, National Bureau of Economic Research, Inc.
    10. Ciani, Emanuele & de Blasio, Guido & Poy, Samuele, 2022. "A freeway to prosperity? Evidence from Calabria, South of Italy," Economics of Transportation, Elsevier, vol. 29(C).
    11. Concetta Rondinelli & Roberta Zizza, 2020. "Spend today or spend tomorrow? The role of inflation expectations in consumer behaviour," Temi di discussione (Economic working papers) 1276, Bank of Italy, Economic Research and International Relations Area.
    12. Park, Sujeong & Powell, David, 2021. "Is the rise in illicit opioids affecting labor supply and disability claiming rates?," Journal of Health Economics, Elsevier, vol. 76(C).
    13. Galassi, Gabriela, 2021. "Labor Demand Response to Labor Supply Incentives: Lessons from the German Mini-Job Reform," IZA Discussion Papers 14248, Institute of Labor Economics (IZA).
    14. Sytsma, Tobias, 2019. "Rules of Origin Liberalization with Multi-Product Firms: Theory and Evidence from Bangladeshi Apparel Exporters," MPRA Paper 95956, University Library of Munich, Germany.
    15. Brendon McConnell, 2023. "What's Logs Got to do With it: On the Perils of log Dependent Variables and Difference-in-Differences," Papers 2308.00167, arXiv.org, revised Aug 2023.
    16. Leider, Julien & Powell, Lisa M., 2022. "Longer-term impacts of the Oakland, California, sugar-sweetened beverage tax on prices and volume sold at two-years post-tax," Social Science & Medicine, Elsevier, vol. 292(C).
    17. David Powell & Rosalie Liccardo Pacula, 2021. "The Evolving Consequences of OxyContin Reformulation on Drug Overdoses," American Journal of Health Economics, University of Chicago Press, vol. 7(1), pages 41-67.
    18. Teemu Makkonen & Timo Mitze, 2021. "Geo-political conflicts, economic sanctions and international knowledge flows," Papers 2112.00564, arXiv.org.
    19. Kastoryano, Stephen & Vollaard, Ben, 2023. "Unseen annihilation: Illegal fishing practices and nautical patrol," Journal of Environmental Economics and Management, Elsevier, vol. 122(C).

    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. Roth, Jonathan & Sant’Anna, Pedro H.C. & Bilinski, Alyssa & Poe, John, 2023. "What’s trending in difference-in-differences? A synthesis of the recent econometrics literature," Journal of Econometrics, Elsevier, vol. 235(2), pages 2218-2244.
    2. Lechner, Michael, 2011. "The Estimation of Causal Effects by Difference-in-Difference Methods," Foundations and Trends(R) in Econometrics, now publishers, vol. 4(3), pages 165-224, November.
    3. Barkowski, Scott, 2021. "Interpretation of nonlinear difference-in-differences: the role of the parallel trends assumption," MPRA Paper 108975, University Library of Munich, Germany.
    4. Jones A.M & Rice N, 2009. "Econometric Evaluation of Health Policies," Health, Econometrics and Data Group (HEDG) Working Papers 09/09, HEDG, c/o Department of Economics, University of York.
    5. Goodman-Bacon, Andrew, 2021. "Difference-in-differences with variation in treatment timing," Journal of Econometrics, Elsevier, vol. 225(2), pages 254-277.
    6. Limwattananon, Supon & Neelsen, Sven & O'Donnell, Owen & Prakongsai, Phusit & Tangcharoensathien, Viroj & van Doorslaer, Eddy & Vongmongkol, Vuthiphan, 2015. "Universal coverage with supply-side reform: The impact on medical expenditure risk and utilization in Thailand," Journal of Public Economics, Elsevier, vol. 121(C), pages 79-94.
    7. Matthew D. Webb, 2023. "Reworking wild bootstrap‐based inference for clustered errors," Canadian Journal of Economics/Revue canadienne d'économique, John Wiley & Sons, vol. 56(3), pages 839-858, August.
    8. Nguyen, Cuong Viet, 2021. "Do weather extremes induce people to move? Evidence from Vietnam," Economic Analysis and Policy, Elsevier, vol. 69(C), pages 118-141.
    9. Sant’Anna, Pedro H.C. & Zhao, Jun, 2020. "Doubly robust difference-in-differences estimators," Journal of Econometrics, Elsevier, vol. 219(1), pages 101-122.
    10. Stefan Boes & Michael Gerfin, 2016. "Does Full Insurance Increase the Demand for Health Care?," Health Economics, John Wiley & Sons, Ltd., vol. 25(11), pages 1483-1496, November.
    11. Ziebarth, Nicolas R. & Karlsson, Martin, 2010. "A natural experiment on sick pay cuts, sickness absence, and labor costs," Journal of Public Economics, Elsevier, vol. 94(11-12), pages 1108-1122, December.
    12. Guido W. Imbens & Jeffrey M. Wooldridge, 2009. "Recent Developments in the Econometrics of Program Evaluation," Journal of Economic Literature, American Economic Association, vol. 47(1), pages 5-86, March.
    13. Erlend E. Bø & Joel Slemrod & Thor O. Thoresen, 2015. "Taxes on the Internet: Deterrence Effects of Public Disclosure," American Economic Journal: Economic Policy, American Economic Association, vol. 7(1), pages 36-62, February.
    14. Supon Limwattananon & Sven Neelsen & Owen O'Donnell & Phusit Prakongsai & Viroj Tangcharoensathien & Eddy van Doorslaer & Vuthiphan Vongmongkol, 2013. "Universal Coverage on a Budget: Impacts on Health Care Utilization and Out-Of-Pocket Expenditures in Thailand," CESifo Working Paper Series 4262, CESifo.
    15. Dang, Hai-Anh H. & Hiraga, Masako & Viet Nguyen, Cuong, 2022. "Childcare and maternal employment: Evidence from Vietnam," World Development, Elsevier, vol. 159(C).
    16. Giuseppe Moscelli & Hugh Gravelle & Luigi Siciliani, 2018. "Effects of Market Structure and Patient Choice on Hospital Quality for Planned Patients," School of Economics Discussion Papers 1118, School of Economics, University of Surrey.
    17. Christian Aleman & Christopher Busch & Alexander Ludwig & Raul Santaeulalia-Llopis, 2022. "A Stage-Based Identification of Policy Effects," PIER Working Paper Archive 22-026, Penn Institute for Economic Research, Department of Economics, University of Pennsylvania.
    18. NicolasR. Ziebarth, 2010. "Estimating Price Elasticities of Convalescent Care Programmes," Economic Journal, Royal Economic Society, vol. 120(545), pages 816-844, June.
    19. Nguyen, Hai V., 2013. "Do smoke-free car laws work? Evidence from a quasi-experiment," Journal of Health Economics, Elsevier, vol. 32(1), pages 138-148.
    20. Ziebarth N, 2009. "“Do I really need to go to rehab? I’d say no, no, no.” Estimating Price Elasticities of Convalescent Care Programs," Health, Econometrics and Data Group (HEDG) Working Papers 09/27, HEDG, c/o Department of Economics, University of York.

    More about this item

    Keywords

    difference-in-differences; log-linearisation; Poisson Pseudo Maximum Likelihood;
    All these keywords.

    JEL classification:

    • C21 - Mathematical and Quantitative Methods - - Single Equation Models; Single Variables - - - Cross-Sectional Models; Spatial Models; Treatment Effect Models
    • C51 - Mathematical and Quantitative Methods - - Econometric Modeling - - - Model Construction and Estimation
    • I38 - Health, Education, and Welfare - - Welfare, Well-Being, and Poverty - - - Government Programs; Provision and Effects of Welfare Programs

    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:bdi:wptemi:td_985_14. 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: the person in charge (email available below). General contact details of provider: https://edirc.repec.org/data/bdigvit.html .

    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.