IDEAS home Printed from
   My bibliography  Save this paper

When Good Instruments Go Bad



This note examines the instrumental variables method used by Neumark, Zhang, and Ciccarella (2005) to analyze Wal-Mart's effect on retail labor markets, and exposes major flaws in that methodology. Neumark, Zhang, and Ciccarella use an interaction between distance from Wal-Mart's headquarters and time effects to predict Wal-Mart's presence in a county, and find that each Wal-Mart store destroys, on average, approximately 200 retail jobs. These findings are in stark contrast to Basker (2005) who found a small, but positive and statistically significant, effect on jobs. I show that the IV estimates obtained by Neumark, Zhang, and Ciccarella confound Wal-Mart's causal effect with other factors. To illustrate the problem, I show that their methodology implies a large impact of Wal-Mart not only on retail employment but also on county manufacturing employment. Reduced-form estimates of the regressions show statistically and economically indistinguishable effects in counties with and without Wal-Mart presence, implying that other factors are most likely driving the results.

Suggested Citation

  • Emek Basker, 2007. "When Good Instruments Go Bad," Working Papers 0706, Department of Economics, University of Missouri.
  • Handle: RePEc:umc:wpaper:0706

    Download full text from publisher

    File URL:
    Download Restriction: no

    References listed on IDEAS

    1. Neumark, David & Zhang, Junfu & Ciccarella, Stephen, 2008. "The effects of Wal-Mart on local labor markets," Journal of Urban Economics, Elsevier, vol. 63(2), pages 405-430, March.
    2. Emek Basker, 2005. "Job Creation or Destruction? Labor Market Effects of Wal-Mart Expansion," The Review of Economics and Statistics, MIT Press, vol. 87(1), pages 174-183, February.
    3. Maluccio, John A., 1998. "Endogeneity of schooling in the wage function," FCND discussion papers 54, International Food Policy Research Institute (IFPRI).
    4. 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.
    5. Jeffrey D. Sachs, 2003. "Institutions Don't Rule: Direct Effects of Geography on Per Capita Income," NBER Working Papers 9490, National Bureau of Economic Research, Inc.
    6. Jinyong Hahn & Jerry Hausman, 2002. "A New Specification Test for the Validity of Instrumental Variables," Econometrica, Econometric Society, vol. 70(1), pages 163-189, January.
    7. Thomas J. Holmes & John J. Stevens, 2004. "Geographic concentration and establishment size: analysis in an alternative economic geography model," Journal of Economic Geography, Oxford University Press, vol. 4(3), pages 227-250, June.
    8. Thomas J. Holmes, 2006. "The Diffusion of Wal-Mart and Economies of Density," 2006 Meeting Papers 15, Society for Economic Dynamics.
    9. repec:fth:prinin:311 is not listed on IDEAS
    10. Thomas J. Kane & Cecilia E. Rouse, 1993. "Labor Market Returns to Two- and Four-Year Colleges: Is a Credit a Credit and Do Degrees Matter?," NBER Working Papers 4268, National Bureau of Economic Research, Inc.
    11. Daron Acemoglu & Joshua Angrist, 1999. "How Large are the Social Returns to Education? Evidence from Compulsory Schooling Laws," NBER Working Papers 7444, National Bureau of Economic Research, Inc.
    Full references (including those not matched with items on IDEAS)


    Citations are extracted by the CitEc Project, subscribe to its RSS feed for this item.

    Cited by:

    1. Fernando Borraz & Juan Dubra & Daniel Ferrés & Leandro Zipitría, 2014. "Supermarket Entry and the Survival of Small Stores," Review of Industrial Organization, Springer;The Industrial Organization Society, vol. 44(1), pages 73-93, February.
    2. Charles Courtemanche & Art Carden, 2014. "Competing with Costco and Sam's Club: Warehouse Club Entry and Grocery Prices," Southern Economic Journal, Southern Economic Association, vol. 80(3), pages 565-585, January.
    3. Fernando Borraz & Juan Dubra & Daniel Ferrés & Leandro Zipitría, 2013. "Supermarket Entry and The Survival of Small Stores," Documentos de Trabajo/Working Papers 1303, Facultad de Ciencias Empresariales y Economia. Universidad de Montevideo..
    4. Basker, Emek, 2011. "The Causes and Consequences of Wal-Mart’s Growth," Economic Policy, Russian Presidential Academy of National Economy and Public Administration, vol. 5, pages 110-134.
    5. Bonanno, Alessandro & Lopez, Rigoberto A., 2009. "Is Wal-Mart a Monopsony? Evidence from Local Labor Markets," 2009 Conference, August 16-22, 2009, Beijing, China 51289, International Association of Agricultural Economists.
    6. John Haltiwanger & Ron Jarmin & C. J. Krizan, 2010. "Mom-and-Pop Meet Big Box: Complements or Substitutes?," NBER Chapters,in: Cities and Entrepreneurship National Bureau of Economic Research, Inc.
    7. Courtemanche, Charles & Carden, Art, 2011. "Supersizing supercenters? The impact of Walmart Supercenters on body mass index and obesity," Journal of Urban Economics, Elsevier, vol. 69(2), pages 165-181, March.
    8. Fabiano Schivardi & Eliana Viviano, 2011. "Entry Barriers in Retail Trade," Economic Journal, Royal Economic Society, vol. 121(551), pages 145-170, March.
    9. Emek Basker & Javier Miranda, 2014. "Taken By Storm: Business Survival In The Aftermath Of Hurricane Katrina," Working Papers 14-20, Center for Economic Studies, U.S. Census Bureau.
    10. Emek Basker, 2011. "Does Wal‐Mart Sell Inferior Goods?," Economic Inquiry, Western Economic Association International, vol. 49(4), pages 973-981, October.
    11. Emek Basker & Javier Miranda, 2014. "Taken by Storm: Business Financing, Survival, and Contagion in the Aftermath of Hurricane Katrina," Working Papers 1406, Department of Economics, University of Missouri, revised 23 Oct 2014.
    12. Courtemanche, Charles & Carden, Art, 2009. "The skinny on big box retailing: Wal-Mart, warehouse clubs, and obesity," MPRA Paper 25326, University Library of Munich, Germany.
    13. Bonanno, Alessandro & Lopez, Rigoberto A., 2012. "Wal-Mart's monopsony power in metro and non-metro labor markets," Regional Science and Urban Economics, Elsevier, vol. 42(4), pages 569-579.

    More about this item


    Instrumental Variables; Wal-Mart; Retail Employment;

    JEL classification:

    • C21 - Mathematical and Quantitative Methods - - Single Equation Models; Single Variables - - - Cross-Sectional Models; Spatial Models; Treatment Effect Models
    • J21 - Labor and Demographic Economics - - Demand and Supply of Labor - - - Labor Force and Employment, Size, and Structure
    • L81 - Industrial Organization - - Industry Studies: Services - - - Retail and Wholesale Trade; e-Commerce

    NEP fields

    This paper has been announced in the following NEP Reports:


    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:umc:wpaper:0706. 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: (Valerie Kulp). 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 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.

    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.