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Regression Discontinuity Design Can Be Your Friend: Developing Evidence in the Real World. Applied Research Seminar Public Policy Research Center. David Kimball Adriano Udani Department of Political Science, UMSL. Agenda. Purpose Scholarship and Contributions Design Application.
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Regression Discontinuity Design Can Be Your Friend:Developing Evidence in the Real World Applied Research Seminar Public Policy Research Center David Kimball Adriano Udani Department of Political Science, UMSL RD Design and Applications
Agenda • Purpose • Scholarship and Contributions • Design • Application RD Design and Applications
Regression discontinuity design • Method to estimate treatment effects in natural setting • Observed continuous variable and causal variable of interest exhibit a discontinuous increase at a certain threshold • Address confounding factors influencing control and treatment • Empirically verify assumptions • strengthens internal validity • Applies to observations only near “cutoff point” • limits external validity RD Design and Applications
Thistlewaite and campbell (1960) • Impact of scholarships on future academic outcomes • Awards based on test scores, measured against cutoff point (c) • If score > c, then individual receive an award • Estimated treatment effect applies to individuals near the cutoff point • Assume these individuals have similar characteristics • EXCEPT receipt of award RD Design and Applications
Types of RD studies RD Design and Applications
Studies that use rdd • Health • Low birth weight babies (Almond et al. 2010) • Young adults who lose health insurance (Anderson et al. 2012) • Education • U.S. School Bond Referenda (Cellini, Ferreira, and Rothstein 2010) • Management studies • Yelp.com ratings (Anderson and Magruder 2012; Lucas 2012) • Political Science • Split tickets in the Senate (Butler and Butler 2005) • Incumbency effect (Snyder 2005) * • Coattails of Members of Congress (Broockman 2009) • U.K. House of Commons (Eggers and Hainmueller 2009) • Close House Races (Caughey and Sekhon 2011) • U.S. mayoral races (Gerber and Hopkins 2011) RD Design and Applications
RDD: Treatment EFFECT RD Design and Applications Source: Perraillon (2013): http://home.uchicago.edu/~mcoca/docs/hrs_rdd_slides_f.pdf
Black Mayors hire more black police Source: Hopkins and McCabe 2012 RD Design and Applications
Evaluate RD Assumption Theoretically • Be wary of RD design if there is strategic behavior or manipulation near threshold. • Information • Incentives • Capacity RD Design and Applications
Test RD assumptions Empirically • Balance test: Plotting means of pre-treament covariates in control group vs. treatment group (difference of means). • Density test: Examine distribution of observations just above and just below threshold. • Test causal direction (outcome or treatment DOES NOT predict pre-treatment DV or other covariates) • Placebo test: Look for other discontinuities in the range of scores. RD Design and Applications
Check Stability of RD REsults • Test different specifications. • Linear • Polynomial • Local regression • Test different “discontinuity samples” (different bandwidths). • Test sensitivity to inclusion of pretreatment covariates RD Design and Applications
Missouri Schools Application RD Design and Applications
Implications for Policy Analysis • RD design is an appealing form of natural experiment. • Weak assumptions compared to other empirical methods • In many cases the assumptions are plausible • Policymakers might consider a threshold for policy applications – this would favor empirical analysis of the policy’s impact. RD Design and Applications
References • Joshua D. Angrist and Jörn-Steffen Pischke, Mostly Harmless Econometrics (Princeton University Press, 2008). • Thad Dunning, Natural Experiments in the Social Sciences (Cambridge University Press, 2012). • Andrew C. Eggers, Anthony Fowler, Jens Hainmueller, Andrew B. Hall, and James M. Snyder, Jr. 2014. “On the Validity of the Regression Discontinuity Design for Estimating Electoral Effects: New Evidence from over 40,000 Close Races.” American Journal of Political Science (May 2014). RD Design and Applications