Well consider widely used key methodologies, as well as more novel approaches. The all option is necessary to install the accompanying dataset used in further examples. Since then, these methods have been applied to diverse research topics. Before you can run this do le, you will need to install the synth program.
For estimating the development of the treated unit in absence of the treatment, the basic idea of scm is to find suitable donor weights which describe how the treated unit is synthesized by a weighted mix of unaffected control units. If you have lots of covariates, you can build the synthetic control based on a subset x1. Apr 23, 2014 the synthetic control method provides a systematic way to choose comparison units in comparative case studies. You might check the websites of the authors of the papers you are referencing to see if they have software. Synthetic control methods for comparative case studies. Estimating the effect of californias tobacco control. I am trying to make graphs for the placebo tests under synthetic control, however i seem to be doing something wrong as i am not being able to merge the files. If you have both a long times series and lots of covariates you can combined the previous two strategies. The synthetic control methodology abadie and gardeazabal, 2003. Then use x2 to assess how close the synthetic control is to the treatment group on those x2 variables. Question on synthetic control methods in stata multiple. Nonparametric synthetic control method for program. Journal of statistical software, june 2011, volume 42.
Causal inference with interactive fixed effects models. The synthetic control method provides a systematic way to choose comparison units in comparative case studies. R package for generalized synthetic control method. In their seminal papers, abadie and gardeazabal2003 as well asabadie, diamond and hainmueller2010 introduced the application of synthetic control methods scm to comparative case studies. Abadie and gardeazabal 2003 pioneered a synthetic control method when estimating the effects of the terrorist conflict in the basque country. This finding holds irrespective of how important these covariates are for accurately. Abadie, alberto, alexis diamond and jens hainmueller. In this section we have brie y described and motivated the synthetic control method. This comparison is used to estimate what would have happened to the treatment group if it.
It seems that there have been a few recent papers who outline methodologies to essentially take synthetic control methods and. Synthetic control modeling questions economics job. These techniques are particularly wellsuited to investigate events occurring at an aggregate level i. Statistical software components from boston college department of economics. The former reweights control units such that the averages of the pretreatment outcomes and covariates are approximately equal between the treatment and. This systematization opens the door to precise quantitative inference in small. If the magnitude of the difference remains in favor of the original treatment group, you can claim that there is a treatment effect. Alexis diamond is evaluation officer, the international finance. Stata module to implement synthetic control methods.
It includes two estimators, mean balancing and kernel balancing. As a prerequisite, the synth package needs to be installed. Automation for multiple synthetic control estimations in stata. Californias large scale tobacco control program on cigarette consumption in. Estimating the effect of californias tobacco control program. Mit department of economics the morris and sophie chang building 50 memorial drive. An r package for synthetic control methods in comparative case studies. Fast and reliable computation of generalized synthetic. In their seminal papers,abadie and gardeazabal2003 as well asabadie, diamond and hainmueller2010 introduced the application of synthetic control methods scm to comparative case studies. Stata module to implement nonparametric synthetic control method.
The synthetic control method is a statistical method used to evaluate the effect of an intervention in comparative case studies. Abadie, diamond, and hainmueller, 2010 as a way to. See abadie and gardeazabal 2003 and abadie, diamond, and hainmueller 2010 for details. We demonstrate both theoretically and empirically that using all outcome lags as separate predictors renders all other covariates irrelevant. Question on synthetic control methods in stata multiple treated units. As a tool for policy evaluation, abadie and gardeazabal 2003 have introduced socalled synthetic control methods scm. Building on an idea in abadie and gardeazabal 2003, this article investigates the application of synthetic control methods to comparative case studies. Journal of statistical software, june 2011, volume 42, issue, p. The synthetic control method as a tool to understand state policy. Stata module to implement synthetic control methods for comparative case studies, statistical software components s457334, boston college department of economics, revised 09 may 2020. Synthetic control modeling questions economics job market.
Synthetic control methodology as a tool for evaluating. Relative to small sample studies, the synthetic control method helps in the selection of comparison cases and opens the door to a method of quantitative inference. Pdf comparative politics and the synthetic control method. While the estimation of the causal effect is a canned procedure in stata, the inference program is not canned.
Health economics, law and economics, labor studies, public economics. Tobacco control program alberto abadie harvard university and nber alexis diamond ifc, world bank group jens hainmueller mit june 2009 abstract building on an idea in abadie and gardeazabal 2003, this article investigates the application of synthetic control methods to comparative case studies. This module should be installed from within stata by typing ssc install synth. Kennedy school of government, harvard university, 79 john f. Synthetic control methods for compar ativ e case studies. First, we implement the synthetic control method with the stata package synth, 18 replicating the specifications used in abadie et al, 10 in which predictors of cigarette sales include retail. Estimating the effect of californias tobacco control program alberto abadie,alexisdiamond, and jens hainmueller building on an idea in abadie and gardeazabal 2003, this article investigates the application of synthetic control methods to comparative case studies. Comparative politics and the synthetic control method. I am using the dataset of abadie2010 and using the command given under help synth to perform the placebo tests, however i. The model assumes that the treated unit such as a country, a region, a city. By alberto abadie, alexis diamond and jens hainmueller.
It is becoming increasingly popular in applications of synthetic control methods to include the entire pretreatment path of the outcome variable as economic predictors. Abadie, diamond, and hainmueller, 2010, journal of the american statistical association 105. Synth is a statistical software that implements synthetic control methods for causal inference in comparative case studies with aggregate data as described in abadie and gardeazabal 2003, abadie, diamond, and hainmueller2010, and abadie, diamond, and hainmueller 20. Synth is a statistical software that implements synthetic control methods for. R code used in this demonstration can be downloaded from here. This synthetic control unit is created as a weighted combination of a collection of jcontrol units, the socalled donor pool. Synthetic control group dear stata users i would like to know if someone had problems running the synthetic control group program synth by alberto abadie. Placebo tests in synthetic control method cross validated. The r package synth implements synthetic control methods for comparative case studies designed to estimate the causal effects of policy interventions and other events of interest abadie and gardeazabal 2003. We find that their results are not being reproduced when alternative software packages are used or when the variables ordering within the dataset is changed. It involves the construction of a weighted combination of groups used as controls, to which the treatment group is compared.
Hi all, new user here, so apologies if this is the wrong forum etc. Mit department of economics the morris and sophie chang building 50 memorial drive building e52, room 546. For each analysis, we used stata 15 and the synth command to employ the synthetic control method abadie et al. R code used in this demonstration can be downloaded from here main reference.
Hainmueller journal of the american statistical association, june 2010, 105490, 493505. The credibility of the result relies on achieving a good preimplementation fit for the outcome of interest between treated unit and synthetic. Trajecotry balancing provides a general reweighting approach to causal inference with timeseries crosssectional tscs data in a differenceindifferences setup. We show that this failure stems from the crossvalidation technique relying on non. Companion software developed by the authors synth package for matlab, r, and stata is available at the authors webpages. The synthetic control method as a tool to understand state. We nish it by taking stock of the main advantages of the synthetic control method.
The synth package for r is also described in detail in abadie,diamond, and. Synthetic control methods abadie and gardeazabal, 2003. Fast and reliable computation of generalized synthetic controls. We discuss the advantages of these methods and apply them to study the effects of proposition 99, a large. Once a month we discuss a particular research method that may be of interest to people working in health economics. Results advantages of the synthetic control method are that it offers an approach suitable when there is a small number of treated units and control units and it does not rely on parallel preimplementation trends like difference in difference methods. It conducts placebo estimates inspace estimations for the same treatment period but on all the. Because a synthetic control is a weighted average of the available control units, the synthetic control method makes explicit 1 the relative contribution of each control unit to the counterfactual of interest. This comparison is used to estimate what would have happened to the treatment group if it had not received the treatment. Im analysing the effects of new financial regulation on firms in malaysia, and im thinking about using synthetic control methods as a way of generating a counterfactual to proxy as untreated malaysian firms. We discuss the advantages of these methods and apply them to study the effects of proposition 99, a largescale tobacco control program that california implemented in 1988. Synth is a statistical software that implements synthetic control methods for causal inference in comparative case studies with aggregate data as described in abadie and gardeazabal 2003, abadie, diamond, and hainmueller 2010, and abadie, diamond, and hainmueller 20.