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Difference in difference meets generalized least squares: Higher order properties of hypotheses tests


  • Hausman, Jerry
  • Kuersteiner, Guido


We investigate the estimation and inference in difference in difference econometric models used in the analysis of treatment effects. When the innovations in such models display serial correlation, commonly used ordinary least squares (OLS) procedures are inefficient and may lead to tests with incorrect size. Implementation of feasible generalized least squares (FGLS) procedures is often hindered by too few observations in the cross-section to allow for unrestricted estimation of the weight matrix without leading to tests with similar size distortions as conventional OLS based procedures. We analyze the small sample properties of FGLS based tests with a formal higher order Edgeworth expansion that allows us to construct a size corrected version of the test. We also address the question of optimal temporal aggregation as a method to reduce the dimension of the weight matrix. We apply our procedure to data on regulation of mobile telephone service prices. We find that a size corrected FGLS based test outperforms tests based on OLS.

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  • Hausman, Jerry & Kuersteiner, Guido, 2008. "Difference in difference meets generalized least squares: Higher order properties of hypotheses tests," Journal of Econometrics, Elsevier, vol. 144(2), pages 371-391, June.
  • Handle: RePEc:eee:econom:v:144:y:2008:i:2:p:371-391

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    References listed on IDEAS

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    Cited by:

    1. Karlsson, Martin & Nilsson, Therese & Pichler, Stefan, 2012. "What Doesn't Kill You Makes You Stronger? The Impact of the 1918 Spanish Flu Epidemic on Economic Performance in Sweden," Working Paper Series 911, Research Institute of Industrial Economics.
    2. Sudip Ranjan Basu & Victor Ognivtsev & Miho Shirotori, 2009. "Building Trade-Relating Institutions And Wto Accession," UNCTAD Blue Series Papers 41, United Nations Conference on Trade and Development.
    3. Avi Dor & William Encinosa & Kathleen Carey, 2016. "Do Good Reports Mean Higher Prices? The Impact of Hospital Compare Ratings on Cardiac Pricing," NBER Working Papers 22858, National Bureau of Economic Research, Inc.
    4. repec:zbw:espost:171454 is not listed on IDEAS
    5. Hausman, Jerry & Palmer, Christopher, 2012. "Heteroskedasticity-robust inference in finite samples," Economics Letters, Elsevier, vol. 116(2), pages 232-235.
    6. repec:fgv:eesptd:411 is not listed on IDEAS
    7. Ben Vollaard, 2005. "Police numbers up, crime rates down. The effect of police on crime in the Netherlands, 1996-2003," Law and Economics 0501006, EconWPA.
    8. Sudip Ranjan Basu, 2008. "Does WTO accession affect domestic economic policies and institutions?," IHEID Working Papers 03-2008, Economics Section, The Graduate Institute of International Studies, revised Feb 2008.
    9. A. Colin Cameron & Douglas L. Miller, 2015. "A Practitioner’s Guide to Cluster-Robust Inference," Journal of Human Resources, University of Wisconsin Press, vol. 50(2), pages 317-372.
    10. A. Colin Cameron & Douglas L. Miller, 2010. "Robust Inference with Clustered Data," Working Papers 107, University of California, Davis, Department of Economics.

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