A Practitioner’s Guide to Cluster-Robust Inference
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- James H. Stock & Mark W. Watson, 2008.
"Heteroskedasticity-Robust Standard Errors for Fixed Effects Panel Data Regression,"
Econometrica, Econometric Society, vol. 76(1), pages 155-174, January.
- James H. Stock & Mark W. Watson, 2006. "Heteroskedasticity-Robust Standard Errors for Fixed Effects Panel Data Regression," NBER Technical Working Papers 0323, National Bureau of Economic Research, Inc.
- Stock, James H. & Watson, Mark, 2008. "Heteroskedasticity-Robust Standard Errors for Fixed Effects Panel Data Regression," Scholarly Articles 28461843, Harvard University Department of Economics.
- Guido W. Imbens & Michal Kolesár, 2016.
"Robust Standard Errors in Small Samples: Some Practical Advice,"
The Review of Economics and Statistics, MIT Press, vol. 98(4), pages 701-712, October.
- Guido W. Imbens & Michal Kolesar, 2012. "Robust Standard Errors in Small Samples: Some Practical Advice," NBER Working Papers 18478, National Bureau of Economic Research, Inc.
- Lara Shore-Sheppard, 1996. "The Precision of Instrumental Variables Estimates With Grouped Data," Working Papers 753, Princeton University, Department of Economics, Industrial Relations Section..
- Kleibergen, Frank & Paap, Richard, 2006.
"Generalized reduced rank tests using the singular value decomposition,"
Journal of Econometrics, Elsevier, vol. 133(1), pages 97-126, July.
- Frank Kleibergen & Richard Paap, 2003. "Generalized Reduced Rank Tests using the Singular Value Decomposition," Tinbergen Institute Discussion Papers 03-003/4, Tinbergen Institute.
- Richard Paap & Frank Kleibergen, 2004. "Generalized Reduced Rank Tests using the Singular Value Decomposition," Econometric Society 2004 Australasian Meetings 195, Econometric Society.
- Kleibergen, F.R. & Paap, R., 2003. "Generalized Reduced Rank Tests using the Singular Value Decomposition," Econometric Institute Research Papers EI 2003-01, Erasmus University Rotterdam, Erasmus School of Economics (ESE), Econometric Institute.
- Timothy G. Conley & Christopher R. Taber, 2011.
"Inference with "Difference in Differences" with a Small Number of Policy Changes,"
The Review of Economics and Statistics, MIT Press, vol. 93(1), pages 113-125, February.
- Timothy Conley & Christopher Taber, 2005. "Inference with "Difference in Differences" with a Small Number of Policy Changes," NBER Technical Working Papers 0312, National Bureau of Economic Research, Inc.
- 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.
- Matthew D. Webb, 2014. "Reworking Wild Bootstrap Based Inference For Clustered Errors," Working Paper 1315, Economics Department, Queen's University.
- Thompson, Samuel B., 2011. "Simple formulas for standard errors that cluster by both firm and time," Journal of Financial Economics, Elsevier, vol. 99(1), pages 1-10, January.
- Keith Finlay & Leandro M. Magnusson, 2009.
"Implementing weak-instrument robust tests for a general class of instrumental-variables models,"
Stata Journal, StataCorp LP, vol. 9(3), pages 398-421, September.
- Keith Finlay & Leandro M. Magnusson, 2009. "Implementing Weak Instrument Robust Tests for a General Class of Instrumental Variables Models," Working Papers 0901, Tulane University, Department of Economics.
- Chernozhukov, Victor & Hansen, Christian, 2008. "The reduced form: A simple approach to inference with weak instruments," Economics Letters, Elsevier, vol. 100(1), pages 68-71, July.
- Kline Patrick & Santos Andres, 2012.
"A Score Based Approach to Wild Bootstrap Inference,"
Journal of Econometric Methods, De Gruyter, vol. 1(1), pages 23-41, August.
- Patrick M. Kline & Andres Santos, 2010. "A Score Based Approach to Wild Bootstrap Inference," NBER Working Papers 16127, National Bureau of Economic Research, Inc.
- Andrews,Donald W. K. & Stock,James H. (ed.), 2005. "Identification and Inference for Econometric Models," Cambridge Books, Cambridge University Press, number 9780521844413, September.
- Blundell,Richard & Newey,Whitney K. & Persson,Torsten (ed.), 2007. "Advances in Economics and Econometrics," Cambridge Books, Cambridge University Press, number 9780521871532, September.
- Jeffrey M Wooldridge, 2010.
"Econometric Analysis of Cross Section and Panel Data,"
MIT Press Books,
The MIT Press,
edition 2, volume 1, number 0262232588, April.
- Jeffrey M. Wooldridge, 2001. "Econometric Analysis of Cross Section and Panel Data," MIT Press Books, The MIT Press, edition 1, volume 1, number 0262232197, April.
- 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.
- Jerry Hausman & Guido Kuersteiner, 2005. "Difference in Difference Meets Generalized Least Squares: Higher Order Properties of Hypotheses Tests," Boston University - Department of Economics - Working Papers Series WP2005-010, Boston University - Department of Economics.
- Andrew V. Carter & Kevin T. Schnepel & Douglas G. Steigerwald, 2017. "Asymptotic Behavior of a t -Test Robust to Cluster Heterogeneity," The Review of Economics and Statistics, MIT Press, vol. 99(4), pages 698-709, July.
- Mitchell A. Petersen, 2009.
"Estimating Standard Errors in Finance Panel Data Sets: Comparing Approaches,"
The Review of Financial Studies, Society for Financial Studies, vol. 22(1), pages 435-480, January.
- Mitchell A. Petersen, 2005. "Estimating Standard Errors in Finance Panel Data Sets: Comparing Approaches," NBER Working Papers 11280, National Bureau of Economic Research, Inc.
- John C. Driscoll & Aart C. Kraay, 1998. "Consistent Covariance Matrix Estimation With Spatially Dependent Panel Data," The Review of Economics and Statistics, MIT Press, vol. 80(4), pages 549-560, November.
- Joshua D. Angrist & Jörn-Steffen Pischke, 2009. "Mostly Harmless Econometrics: An Empiricist's Companion," Economics Books, Princeton University Press, edition 1, number 8769.
- Blundell,Richard & Newey,Whitney & Persson,Torsten (ed.), 2007. "Advances in Economics and Econometrics," Cambridge Books, Cambridge University Press, number 9780521692106, September.
- Greenwald, Bruce C., 1983. "A general analysis of bias in the estimated standard errors of least squares coefficients," Journal of Econometrics, Elsevier, vol. 22(3), pages 323-338, August.
- James G. MacKinnon & Matthew D. Webb, 2017.
"Wild Bootstrap Inference for Wildly Different Cluster Sizes,"
Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 32(2), pages 233-254, March.
- James G. MacKinnon & Matthew D. Webb, 2015. "Wild Bootstrap Inference For Wildly Different Cluster Sizes," Working Paper 1314, Economics Department, Queen's University.
- 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.
- Marianne Bertrand & Esther Duflo & Sendhil Mullainathan, 2002. "How Much Should We Trust Differences-in-Differences Estimates?," NBER Working Papers 8841, National Bureau of Economic Research, Inc.
- Blundell,Richard & Newey,Whitney K. & Persson,Torsten (ed.), 2007. "Advances in Economics and Econometrics," Cambridge Books, Cambridge University Press, number 9780521692090, September.
- Kloek, T, 1981. "OLS Estimation in a Model Where a Microvariable Is Explained by Aggregates and Contemporaneous Disturbances Are Equicorrelated," Econometrica, Econometric Society, vol. 49(1), pages 205-207, January.
- Karla Hemming & Jen Marsh, 2013. "A menu-driven facility for sample-size calculations in cluster randomized controlled trials," Stata Journal, StataCorp LP, vol. 13(1), pages 114-135, March.
- Inoue, Atsushi & Solon, Gary, 2006.
"A Portmanteau Test For Serially Correlated Errors In Fixed Effects Models,"
Econometric Theory, Cambridge University Press, vol. 22(5), pages 835-851, October.
- Atsushi Inoue & Gary Solon, 2005. "A Portmanteau Test for Serially Correlated Errors in Fixed Effects Models," NBER Technical Working Papers 0310, National Bureau of Economic Research, Inc.
- Gary Solon & Steven J. Haider & Jeffrey M. Wooldridge, 2015.
"What Are We Weighting For?,"
Journal of Human Resources, University of Wisconsin Press, vol. 50(2), pages 301-316.
- Gary Solon & Steven J. Haider & Jeffrey Wooldridge, 2013. "What Are We Weighting For?," NBER Working Papers 18859, National Bureau of Economic Research, Inc.
- White, Halbert, 1980. "A Heteroskedasticity-Consistent Covariance Matrix Estimator and a Direct Test for Heteroskedasticity," Econometrica, Econometric Society, vol. 48(4), pages 817-838, May.
- Mesnard, Alice & Vera-Hernández, Marcos & Fitzsimons, Emla & Malde, Bansi, 2012.
"Household Responses to Information on Child Nutrition: Experimental Evidence from Malawi,"
CEPR Discussion Papers
8915, C.E.P.R. Discussion Papers.
- Emla Fitzsimons & Bansi Malde & Alice Mesnard & Marcos Vera-Hernandez, 2012. "Household responses to information on child nutrition: experimental evidence from Malawi," IFS Working Papers W12/07, Institute for Fiscal Studies.
- Joshua D. Angrist & Victor Lavy, 2002.
"The Effect of High School Matriculation Awards: Evidence from Randomized Trials,"
NBER Working Papers
9389, National Bureau of Economic Research, Inc.
- Angrist, Josh & Lavy, Victor, 2002. "The Effect of High School Matriculation Awards: Evidence from Randomized Trials," CEPR Discussion Papers 3827, C.E.P.R. Discussion Papers.
- Newey, Whitney & West, Kenneth, 2014.
"A simple, positive semi-definite, heteroscedasticity and autocorrelation consistent covariance matrix,"
Applied Econometrics, Russian Presidential Academy of National Economy and Public Administration (RANEPA), vol. 33(1), pages 125-132.
- Newey, Whitney K & West, Kenneth D, 1987. "A Simple, Positive Semi-definite, Heteroskedasticity and Autocorrelation Consistent Covariance Matrix," Econometrica, Econometric Society, vol. 55(3), pages 703-708, May.
- Whitney K. Newey & Kenneth D. West, 1986. "A Simple, Positive Semi-Definite, Heteroskedasticity and AutocorrelationConsistent Covariance Matrix," NBER Technical Working Papers 0055, National Bureau of Economic Research, Inc.
- Thomas Barrios & Rebecca Diamond & Guido W. Imbens & Michal Kolesár, 2012.
"Clustering, Spatial Correlations, and Randomization Inference,"
Journal of the American Statistical Association, Taylor & Francis Journals, vol. 107(498), pages 578-591, June.
- Thomas Barrios & Rebecca Diamond & Guido W. Imbens & Michal Kolesar, 2010. "Clustering, Spatial Correlations and Randomization Inference," NBER Working Papers 15760, National Bureau of Economic Research, Inc.
- Davis, Peter, 2002. "Estimating multi-way error components models with unbalanced data structures," Journal of Econometrics, Elsevier, vol. 106(1), pages 67-95, January.
- MacKinnon, James G. & White, Halbert, 1985.
"Some heteroskedasticity-consistent covariance matrix estimators with improved finite sample properties,"
Journal of Econometrics, Elsevier, vol. 29(3), pages 305-325, September.
- James G. MacKinnon & Halbert White, 1983. "Some Heteroskedasticity Consistent Covariance Matrix Estimators with Improved Finite Sample Properties," Working Paper 537, Economics Department, Queen's University.
- Jeffrey M. Wooldridge, 2003. "Cluster-Sample Methods in Applied Econometrics," American Economic Review, American Economic Association, vol. 93(2), pages 133-138, May.
- Bester, C. Alan & Conley, Timothy G. & Hansen, Christian B., 2011. "Inference with dependent data using cluster covariance estimators," Journal of Econometrics, Elsevier, vol. 165(2), pages 137-151.
- Bhattacharya, Debopam, 2005. "Asymptotic inference from multi-stage samples," Journal of Econometrics, Elsevier, vol. 126(1), pages 145-171, May.
- Blundell,Richard & Newey,Whitney & Persson,Torsten (ed.), 2007. "Advances in Economics and Econometrics," Cambridge Books, Cambridge University Press, number 9780521871549, September.
- 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.
- Moulton, Brent R, 1990. "An Illustration of a Pitfall in Estimating the Effects of Aggregate Variables on Micro Unit," The Review of Economics and Statistics, MIT Press, vol. 72(2), pages 334-338, May.
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