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Regression discontinuity: review with extensions

Author

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  • Jin-young Choi

    (Goethe University)

  • Myoung-jae Lee

    (Korea University)

Abstract

In treatment effect analysis, often the treatment takes a particular structure: ‘on’ if an underlying continuous variable crosses a threshold, and ‘off’ otherwise. Such a treatment occurs in various institutional settings such as a test score crossing a threshold to graduate, or income falling below a threshold to qualify for an aid. In this kind of cases, the study design is called ‘regression discontinuity (RD)’, which is popular in analyzing observational data, as long as the treatment takes the required form. This paper reviews RD to convey its essentials, and provides some extensions. First, the main RD idea based on local randomization due to an institutional/legal break is introduced. Second, treatment effects identified by RD are explored. Third, popular RD estimators are reviewed. Fourth, main specification tests are examined. Fifth, special RD topics are reviewed. Also, an empirical illustration is provided.

Suggested Citation

  • Jin-young Choi & Myoung-jae Lee, 2017. "Regression discontinuity: review with extensions," Statistical Papers, Springer, vol. 58(4), pages 1217-1246, December.
    • Handle: RePEc:spr:stpapr:v:58:y:2017:i:4:d:10.1007_s00362-016-0745-z
    DOI: 10.1007/s00362-016-0745-z
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    as
    1. Erich Battistin & Agar Brugiavini & Enrico Rettore & Guglielmo Weber, 2009. "The Retirement Consumption Puzzle: Evidence from a Regression Discontinuity Approach," American Economic Review, American Economic Association, vol. 99(5), pages 2209-2226, December.
    2. Patrick Hullegie & Tobias J. Klein, 2010. "The effect of private health insurance on medical care utilization and self‐assessed health in Germany," Health Economics, John Wiley & Sons, Ltd., vol. 19(9), pages 1048-1062, September.
    3. Frandsen, Brigham R. & Frölich, Markus & Melly, Blaise, 2012. "Quantile treatment effects in the regression discontinuity design," Journal of Econometrics, Elsevier, vol. 168(2), pages 382-395.
    4. Lalive, Rafael, 2008. "How do extended benefits affect unemployment duration A regression discontinuity approach," Journal of Econometrics, Elsevier, vol. 142(2), pages 785-806, February.
    5. David Card & David S. Lee & Zhuan Pei & Andrea Weber, 2015. "Inference on Causal Effects in a Generalized Regression Kink Design," Econometrica, Econometric Society, vol. 83, pages 2453-2483, November.
    6. Alan I. Barreca & Jason M. Lindo & Glen R. Waddell, 2016. "Heaping-Induced Bias In Regression-Discontinuity Designs," Economic Inquiry, Western Economic Association International, vol. 54(1), pages 268-293, January.
    7. Helena Skyt Nielsen & Torben Sørensen & Christopher Taber, 2010. "Estimating the Effect of Student Aid on College Enrollment: Evidence from a Government Grant Policy Reform," NBER Chapters, in: Income Taxation, Trans-Atlantic Public Economics Seminar (TAPES), pages 185-215, National Bureau of Economic Research, Inc.
    8. Otsu, Taisuke & Xu, Ke-Li & Matsushita, Yukitoshi, 2015. "Empirical likelihood for regression discontinuity design," Journal of Econometrics, Elsevier, vol. 186(1), pages 94-112.
    9. Miguel Urquiola & Eric Verhoogen, 2009. "Class-Size Caps, Sorting, and the Regression-Discontinuity Design," American Economic Review, American Economic Association, vol. 99(1), pages 179-215, March.
    10. David S. Lee & Thomas Lemieux, 2010. "Regression Discontinuity Designs in Economics," Journal of Economic Literature, American Economic Association, vol. 48(2), pages 281-355, June.
    11. Douglas Almond & Joseph J. Doyle & Amanda E. Kowalski & Heidi Williams, 2010. "Estimating Marginal Returns to Medical Care: Evidence from At-risk Newborns," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 125(2), pages 591-634.
    12. Alan I. Barreca & Melanie Guldi & Jason M. Lindo & Glen R. Waddell, 2011. "Saving Babies? Revisiting the effect of very low birth weight classification," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 126(4), pages 2117-2123.
    13. Sebastian Calonico & Matias D. Cattaneo & Rocio Titiunik, 2014. "Robust Nonparametric Confidence Intervals for Regression‐Discontinuity Designs," Econometrica, Econometric Society, vol. 82, pages 2295-2326, November.
    14. Marinho Bertanha & Guido W. Imbens, 2020. "External Validity in Fuzzy Regression Discontinuity Designs," Journal of Business & Economic Statistics, Taylor & Francis Journals, vol. 38(3), pages 593-612, July.
    15. Brian A. Jacob & Lars Lefgren, 2004. "Remedial Education and Student Achievement: A Regression-Discontinuity Analysis," The Review of Economics and Statistics, MIT Press, vol. 86(1), pages 226-244, February.
    16. Jörg Breitung & Robinson Kruse, 2013. "When bubbles burst: econometric tests based on structural breaks," Statistical Papers, Springer, vol. 54(4), pages 911-930, November.
    17. Wilbert Van Der Klaauw, 2008. "Regression–Discontinuity Analysis: A Survey of Recent Developments in Economics," LABOUR, CEIS, vol. 22(2), pages 219-245, June.
    18. Lee, Myoung-jae, 2005. "Micro-Econometrics for Policy, Program and Treatment Effects," OUP Catalogue, Oxford University Press, number 9780199267699.
    19. Gabriela Ciuperca, 2014. "Model selection by LASSO methods in a change-point model," Statistical Papers, Springer, vol. 55(2), pages 349-374, May.
    20. Young-sook Kim & Myoung-jae Lee, 2016. "Regression-Kink Approach for Wage Effect on Male Work Hours," Oxford Bulletin of Economics and Statistics, Department of Economics, University of Oxford, vol. 78(3), pages 424-442, June.
    21. Jens Ludwig & Douglas L. Miller, 2007. "Does Head Start Improve Children's Life Chances? Evidence from a Regression Discontinuity Design," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 122(1), pages 159-208.
    22. Takahide Yanagi, 2014. "The Effect of Measurement Error in the Sharp Regression Discontinuity Design," KIER Working Papers 910, Kyoto University, Institute of Economic Research.
    23. Marco Caliendo & Konstantinos Tatsiramos & Arne Uhlendorff, 2013. "Benefit Duration, Unemployment Duration And Job Match Quality: A Regression‐Discontinuity Approach," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 28(4), pages 604-627, June.
    24. John M. MacDonald & Jonathan Klick & Ben Grunwald, 2016. "The effect of private police on crime: evidence from a geographic regression discontinuity design," Journal of the Royal Statistical Society Series A, Royal Statistical Society, vol. 179(3), pages 831-846, June.
    25. Edwin Leuven & Mikael Lindahl & Hessel Oosterbeek & Dinand Webbink, 2007. "The Effect of Extra Funding for Disadvantaged Pupils on Achievement," The Review of Economics and Statistics, MIT Press, vol. 89(4), pages 721-736, November.
    26. Johannes F. Schmieder† & Till von Wachter & Stefan Bender, 2011. "The Effects Of Extended Unemployment Insurance Over The Business Cycle: Evidence From Regression Discontinuity Estimates Over Twenty Years," Boston University - Department of Economics - Working Papers Series WP2011-063, Boston University - Department of Economics.
    27. Taisuke Otsu & Ke-Li Xu & Yukitoshi Matsushita, 2013. "Estimation and Inference of Discontinuity in Density," Journal of Business & Economic Statistics, Taylor & Francis Journals, vol. 31(4), pages 507-524, October.
    28. Feir, Donna & Lemieux, Thomas & Marmer, Vadim, 2014. "Supplement To "Weak Identification in Fuzzy Regression Discontinuity Designs"," Microeconomics.ca working papers vadim_marmer-2014-3, Vancouver School of Economics, revised 02 Mar 2015.
    29. Sebastian Calonico & Matias D. Cattaneo & Rocío Titiunik, 2015. "Optimal Data-Driven Regression Discontinuity Plots," Journal of the American Statistical Association, Taylor & Francis Journals, vol. 110(512), pages 1753-1769, December.
    30. Cook, Thomas D., 2008. ""Waiting for Life to Arrive": A history of the regression-discontinuity design in Psychology, Statistics and Economics," Journal of Econometrics, Elsevier, vol. 142(2), pages 636-654, February.
    31. S. Derya Uysal, 2015. "Doubly Robust Estimation of Causal Effects with Multivalued Treatments: An Application to the Returns to Schooling," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 30(5), pages 763-786, August.
    32. Imbens, Guido W & Angrist, Joshua D, 1994. "Identification and Estimation of Local Average Treatment Effects," Econometrica, Econometric Society, vol. 62(2), pages 467-475, March.
    33. Guido Imbens & Karthik Kalyanaraman, 2012. "Optimal Bandwidth Choice for the Regression Discontinuity Estimator," The Review of Economic Studies, Review of Economic Studies Ltd, vol. 79(3), pages 933-959.
    34. Yingying Dong & Arthur Lewbel, 2015. "Identifying the Effect of Changing the Policy Threshold in Regression Discontinuity Models," The Review of Economics and Statistics, MIT Press, vol. 97(5), pages 1081-1092, December.
    35. Bertanha, Marinho, 2020. "Regression discontinuity design with many thresholds," Journal of Econometrics, Elsevier, vol. 218(1), pages 216-241.
    36. Myoung‐jae Lee, 2000. "Median treatment effect in randomized trials," Journal of the Royal Statistical Society Series B, Royal Statistical Society, vol. 62(3), pages 595-604.
    37. Erich Battistin & Enrico Rettore, 2002. "Testing for programme effects in a regression discontinuity design with imperfect compliance," Journal of the Royal Statistical Society Series A, Royal Statistical Society, vol. 165(1), pages 39-57, February.
    38. Wilbert van der Klaauw, 2002. "Estimating the Effect of Financial Aid Offers on College Enrollment: A Regression-Discontinuity Approach," International Economic Review, Department of Economics, University of Pennsylvania and Osaka University Institute of Social and Economic Research Association, vol. 43(4), pages 1249-1287, November.
    39. Richard Dickens & Rebecca Riley & David Wilkinson, 2014. "The UK minimum wage at 22 years of age: a regression discontinuity approach," Journal of the Royal Statistical Society Series A, Royal Statistical Society, vol. 177(1), pages 95-114, January.
    40. Imbens, Guido W. & Lemieux, Thomas, 2008. "Regression discontinuity designs: A guide to practice," Journal of Econometrics, Elsevier, vol. 142(2), pages 615-635, February.
    41. Keele, Luke J. & Titiunik, Rocío, 2015. "Geographic Boundaries as Regression Discontinuities," Political Analysis, Cambridge University Press, vol. 23(1), pages 127-155, January.
    42. Gerard, Francois & Rokkanen, Miikka & Rothe, Christoph, 2015. "Identification and Inference in Regression Discontinuity Designs with a Manipulated Running Variable," IZA Discussion Papers 9604, Institute of Labor Economics (IZA).
    43. Fabrizia Mealli & Carla Rampichini, 2012. "Evaluating the effects of university grants by using regression discontinuity designs," Journal of the Royal Statistical Society Series A, Royal Statistical Society, vol. 175(3), pages 775-798, July.
    44. McCrary, Justin, 2008. "Manipulation of the running variable in the regression discontinuity design: A density test," Journal of Econometrics, Elsevier, vol. 142(2), pages 698-714, February.
    45. Johannes F. Schmieder & Till von Wachter & Stefan Bender, 2012. "The Effects of Extended Unemployment Insurance Over the Business Cycle: Evidence from Regression Discontinuity Estimates Over 20 Years," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 127(2), pages 701-752.
    46. Papay, John P. & Willett, John B. & Murnane, Richard J., 2011. "Extending the regression-discontinuity approach to multiple assignment variables," Journal of Econometrics, Elsevier, vol. 161(2), pages 203-207, April.
    47. Douglas Almond & Joseph J. Doyle & Amanda E. Kowalski & Heidi Williams, 2011. "The Role of Hospital Heterogeneity in Measuring Marginal Returns to Medical Care: A Reply to Barreca, Guldi, Lindo, and Waddell," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 126(4), pages 2125-2131.
    48. Lee, David S. & Card, David, 2008. "Regression discontinuity inference with specification error," Journal of Econometrics, Elsevier, vol. 142(2), pages 655-674, February.
    49. Richard Dickens & Rebecca Riley & David Wilkinson, 2011. "The UK Minimum Wage at Age 22: A Regression Discontinuity Approach," Working Paper Series 2111, Department of Economics, University of Sussex Business School.
    50. Joshua D. Angrist & Miikka Rokkanen, 2015. "Wanna Get Away? Regression Discontinuity Estimation of Exam School Effects Away From the Cutoff," Journal of the American Statistical Association, Taylor & Francis Journals, vol. 110(512), pages 1331-1344, December.
    51. Hahn, Jinyong & Todd, Petra & Van der Klaauw, Wilbert, 2001. "Identification and Estimation of Treatment Effects with a Regression-Discontinuity Design," Econometrica, Econometric Society, vol. 69(1), pages 201-209, January.
    52. Joseph C. Cappelleri & William M.K. Trochim & T.D. Stanley & Charles S. Reichardt, 1991. "Random Measurement Error Does Not Bias the Treatment Effect Estimate in the Regression-Discontinuity Design," Evaluation Review, , vol. 15(4), pages 395-419, August.
    53. Diane Whitmore Schanzenbach, 2009. "Do School Lunches Contribute to Childhood Obesity?," Journal of Human Resources, University of Wisconsin Press, vol. 44(3).
    54. Ben B. Hansen, 2008. "The prognostic analogue of the propensity score," Biometrika, Biometrika Trust, vol. 95(2), pages 481-488.
    55. Abadie A., 2002. "Bootstrap Tests for Distributional Treatment Effects in Instrumental Variable Models," Journal of the American Statistical Association, American Statistical Association, vol. 97, pages 284-292, March.
    56. Matsudaira, Jordan D., 2008. "Mandatory summer school and student achievement," Journal of Econometrics, Elsevier, vol. 142(2), pages 829-850, February.
    57. Yingying Dong, 2015. "Regression Discontinuity Applications with Rounding Errors in the Running Variable," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 30(3), pages 422-446, April.
    58. Damon Clark & Paco Martorell, 2014. "The Signaling Value of a High School Diploma," Journal of Political Economy, University of Chicago Press, vol. 122(2), pages 282-318.
    59. Joshua D. Angrist & Victor Lavy, 1999. "Using Maimonides' Rule to Estimate the Effect of Class Size on Scholastic Achievement," The Quarterly Journal of Economics, President and Fellows of Harvard College, vol. 114(2), pages 533-575.
    60. Claire Crawford & Lorraine Dearden & Ellen Greaves, 2014. "The drivers of month-of-birth differences in children's cognitive and non-cognitive skills," Journal of the Royal Statistical Society Series A, Royal Statistical Society, vol. 177(4), pages 829-860, October.
    61. Gabriela Ciuperca, 2014. "Erratum to: Model selection by LASSO methods in a change-point model," Statistical Papers, Springer, vol. 55(4), pages 1231-1232, November.
    62. Porter, Jack & Yu, Ping, 2015. "Regression discontinuity designs with unknown discontinuity points: Testing and estimation," Journal of Econometrics, Elsevier, vol. 189(1), pages 132-147.
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