IDEAS home Printed from
   My bibliography  Save this paper

Extending the difference-in-differences (DID) to settings with many treated units and same intervention time: Model and Stata implementation


  • Giovanni Cerulli

    (IRCrES-CNR, National Research Council of Italy)


The difference-in-differences (DID) estimator is popular to estimate average treatment effects in causal inference studies. Under the common support assumption, DID overcomes the problem of unobservable selection using panel, time, and/or location fixed effects, and the knowledge of the pre/post intervention times. New developments of DID have been recently proposed: (i) the Synthetic Control Method (SCM) applies when a long pre- and post-intervention time series is available, only one unit is treated, and intervention occurs in a specific time (implemented in Stata via SYNTH by Hainmueller, Abadie, Dimond, 2014); (ii) an extension to binary time varying treatment with many treated units, have been also proposed and implemented in Stata via TVDIFF (Cerulli and Ventura, 2018). However, a command to accommodate a setting with many treated units and same intervention time is still lacking. In this presentation, I propose a potential outcome model to accommodate this latter setting, and provide a Stata implementation via the new Stata routine FTMTDIFF (standing for fixed-time multiple treated DID). I will finally set some guidelines for future DID developments.

Suggested Citation

  • Giovanni Cerulli, 2019. "Extending the difference-in-differences (DID) to settings with many treated units and same intervention time: Model and Stata implementation," 2019 Stata Conference 26, Stata Users Group.
  • Handle: RePEc:boc:scon19:26

    Download full text from publisher

    File URL:
    Download Restriction: no

    References listed on IDEAS

    1. Cerulli, Giovanni, 2019. "A flexible Synthetic Control Method for modeling policy evaluation," Economics Letters, Elsevier, vol. 182(C), pages 40-44.
    2. Abadie, Alberto & Diamond, Alexis & Hainmueller, Jens, 2010. "Synthetic Control Methods for Comparative Case Studies: Estimating the Effect of California’s Tobacco Control Program," Journal of the American Statistical Association, American Statistical Association, vol. 105(490), pages 493-505.
    3. David H. Autor, 2003. "Outsourcing at Will: The Contribution of Unjust Dismissal Doctrine to the Growth of Employment Outsourcing," Journal of Labor Economics, University of Chicago Press, vol. 21(1), pages 1-42, January.
    Full references (including those not matched with items on IDEAS)

    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. Asatryan, Zareh & Castellón, César & Stratmann, Thomas, 2018. "Balanced budget rules and fiscal outcomes: Evidence from historical constitutions," Journal of Public Economics, Elsevier, vol. 167(C), pages 105-119.
    2. Alexander S. Skorobogatov, 2021. "The effect of alcohol sales restrictions on alcohol poisoning mortality: Evidence from Russia," Health Economics, John Wiley & Sons, Ltd., vol. 30(6), pages 1417-1442, June.
    3. Chakraborty Avinandan & Doremus Jacqueline & Stith Sarah, 2021. "The effects of recreational cannabis access on labor markets: evidence from Colorado," IZA Journal of Labor Economics, Sciendo & Forschungsinstitut zur Zukunft der Arbeit GmbH (IZA), vol. 10(1), pages 1-86, January.
    4. Shu He & Jing Peng & Jianbin Li & Liping Xu, 2020. "Impact of Platform Owner’s Entry on Third-Party Stores," Information Systems Research, INFORMS, vol. 31(4), pages 1467-1484, December.
    5. Zabinski, Zenon & Black, Bernard S., 2022. "The deterrent effect of tort law: Evidence from medical malpractice reform," Journal of Health Economics, Elsevier, vol. 84(C).
    6. Leonardo Corral & Maja Schling & Cassandra Rogers & Janice Cumberbatch & Fabian Hinds & Naijun Zhou & Michele H. Lemay, 2016. "The Impact of Coastal Infrastructure Improvements on Economic Growth: Evidence from Barbados," IDB Publications (Working Papers) 95978, Inter-American Development Bank.
    7. Bhalotra, Sonia R. & Clarke, Damian & Gomes, Joseph & Venkataramani, Atheendar, 2018. "Maternal Mortality and Women's Political Participation," IZA Discussion Papers 11590, Institute of Labor Economics (IZA).
    8. Maclean, J. Catherine & Tello-Trillo, Sebastian & Webber, Douglas A., 2019. "Losing Insurance and Behavioral Health Hospitalizations: Evidence from a Large-Scale Medicaid Disenrollment," IZA Discussion Papers 12463, Institute of Labor Economics (IZA).
    9. Bueno, Matheus & Valente, Marica, 2019. "The effects of pricing waste generation: A synthetic control approach," Journal of Environmental Economics and Management, Elsevier, vol. 96(C), pages 274-285.
    10. Leonardo M. Giuffrida & Gabriele Rovigatti, 2017. "Can the Private Sector Ensure the Public Interest? Evidence from Federal Procurement," CEIS Research Paper 411, Tor Vergata University, CEIS, revised 20 Jul 2017.
    11. Johanna Catherine Maclean & Sebastian Tello-Trillo & Douglas Webber, 2019. "Losing Insurance and Psychiatric Hospitalizations," NBER Working Papers 25936, National Bureau of Economic Research, Inc.
    12. Dasgupta, Kabir & Mason, Brenden J., 2020. "The effect of interest rate caps on bankruptcy: Synthetic control evidence from recent payday lending bans," Journal of Banking & Finance, Elsevier, vol. 119(C).
    13. Yu, Yang & Jaenicke, Edward C., 2021. "The effect of sell-by dates on purchase volume and food waste," Food Policy, Elsevier, vol. 98(C).
    14. Francesca Caselli, 2017. "Did the Exchange Rate Floor Prevent Deflation in the Czech Republic?," Review of Economics and Institutions, Università di Perugia, vol. 8(2).
    15. Sylvia Allegretto & Arindrajit Dube & Michael Reich & Ben Zipperer, 2017. "Credible Research Designs for Minimum Wage Studies," ILR Review, Cornell University, ILR School, vol. 70(3), pages 559-592, May.
    16. Stefan Seifert & Marica Valente, 2018. "An Offer that you Can't Refuse? Agrimafias and Migrant Labor on Vineyards in Southern Italy," Discussion Papers of DIW Berlin 1735, DIW Berlin, German Institute for Economic Research.
    17. Alessio Mitra & Athanasios Chymis, 2022. "Federalism, but how? The impact of vertical fiscal imbalance on economic growth. Evidence from Belgium," Economics and Politics, Wiley Blackwell, vol. 34(2), pages 322-350, July.
    18. Corral, Leonardo & Schling, Maja & Rogers, Cassandra & Cumberbatch, Janice & Hinds, Fabian & Zhou, Naijun & Lemay, Michele H., 2018. "The Impact of Coastal Infrastructure Improvements on Economic Growth: Evidence from Barbados," IDB Publications (Working Papers) 7860, Inter-American Development Bank.
    19. Sonia Bhalotra & Damian Clarke & Joseph F. Gomes & Atheendar Venkataramani, 2021. "Maternal Mortality and Women’s Political Power," LIDAM Discussion Papers IRES 2021010, Université catholique de Louvain, Institut de Recherches Economiques et Sociales (IRES).
    20. Schumann, Mathias, 2017. "The effects of minimum wages on firm-financed apprenticeship training," Labour Economics, Elsevier, vol. 47(C), pages 163-181.

    More about this item


    Access and download statistics


    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:boc:scon19:26. See general information about how to correct material in RePEc.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: . General contact details of provider: .

    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: Christopher F Baum (email available below). General contact details of provider: .

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

    IDEAS is a RePEc service hosted by the Research Division of the Federal Reserve Bank of St. Louis . RePEc uses bibliographic data supplied by the respective publishers.