[TE] Treatment Effects

1 STATA Treatment - Effects . REFERENCE MANUAL: POTENTIAL OUTCOMES/COUNTERFACTUAL OUTCOMES. RELEASE 13.. A Stata Press Publication StataCorp LP. College Station, Texas . Copyright c 1985 2013 StataCorp LP. All rights reserved Version 13. Published by Stata Press, 4905 Lakeway Drive, College Station, Texas 77845. Typeset in TEX. ISBN-10: 1-59718-128-5. ISBN-13: 978-1-59718-128-0. This manual is protected by copyright. All rights are reserved. No part of this manual may be reproduced, stored in a retrieval system, or transcribed, in any form or by any means electronic, mechanical, photocopy, recording, or otherwise without the prior written permission of StataCorp LP unless permitted subject to the terms and conditions of a license granted to you by StataCorp LP to use the software and documentation.

2 No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document. StataCorp provides this manual as is without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. StataCorp may make improvements and/or changes in the product(s) and the program(s) described in this manual at any time and without notice. The software described in this manual is furnished under a license agreement or nondisclosure agreement. The software may be copied only in accordance with the terms of the agreement.

3 It is against the law to copy the software onto DVD, CD, disk, diskette, tape, or any other medium for any purpose other than backup or archival purposes. The automobile dataset appearing on the accompanying media is Copyright c 1979 by Consumers Union of , Inc., Yonkers, NY 10703-1057 and is reproduced by permission from CONSUMER REPORTS, April 1979. Stata, , Stata Press, Mata, , and NetCourse are registered trademarks of StataCorp LP. Stata and Stata Press are registered trademarks with the World Intellectual Property Organization of the United Nations. NetCourseNow is a trademark of StataCorp LP. Other brand and product names are registered trademarks or trademarks of their respective companies.

4 For copyright information about the software, type help copyright within Stata. The suggested citation for this software is StataCorp. 2013. Stata: Release 13 . Statistical Software. College Station, TX: StataCorp LP. Contents Treatment Effects .. Introduction to Treatment - Effects commands 1. etpoisson .. Poisson regression with endogenous Treatment Effects 2. etpoisson postestimation .. Postestimation tools for etpoisson 14. etregress .. Linear regression with endogenous Treatment Effects 17. etregress postestimation .. Postestimation tools for etregress 31. teffects .. Treatment - Effects estimation for observational data 34.

5 Teffects intro .. Introduction to Treatment Effects for observational data 35. teffects intro advanced .. Advanced introduction to Treatment Effects for observational data 47. teffects aipw .. Augmented inverse-probability weighting 60. teffects ipw .. Inverse-probability weighting 81. teffects ipwra .. Inverse-probability-weighted regression adjustment 89. teffects multivalued .. Multivalued Treatment Effects 98. teffects nnmatch .. Nearest-neighbor matching 107. teffects overlap .. Overlap plots 120. teffects postestimation .. Postestimation tools for teffects 127. teffects psmatch .. Propensity-score matching 134.

6 Teffects ra .. Regression adjustment 142. Glossary .. 153. Subject and author index .. 157. i Cross-referencing the documentation When reading this manual, you will find references to other Stata manuals. For example, [U] 26 Overview of Stata estimation commands [R] regress [D] reshape The first example is a reference to chapter 26, Overview of Stata estimation commands, in the User's Guide; the second is a reference to the regress entry in the Base Reference Manual; and the third is a reference to the reshape entry in the Data Management Reference Manual. All the manuals in the Stata Documentation have a shorthand notation.

7 [GSM] Getting Started with Stata for Mac [GSU] Getting Started with Stata for Unix [GSW] Getting Started with Stata for Windows [U ] Stata User's Guide [R] Stata Base Reference Manual [D ] Stata Data Management Reference Manual [G ] Stata Graphics Reference Manual [XT] Stata Longitudinal-Data/Panel-Data Reference Manual [ME] Stata Multilevel Mixed- Effects Reference Manual [MI] Stata Multiple-Imputation Reference Manual [MV] Stata Multivariate Statistics Reference Manual [PSS] Stata Power and Sample-Size Reference Manual [P ] Stata Programming Reference Manual [SEM] Stata Structural Equation Modeling Reference Manual [SVY] Stata Survey Data Reference Manual [ST] Stata Survival Analysis and Epidemiological Tables Reference Manual [TS] Stata Time-Series Reference Manual [TE] Stata Treatment - Effects Reference Manual: Potential Outcomes/Counterfactual Outcomes [I] Stata Glossary and Index [M ] Mata Reference Manual iii Title Treatment Effects Introduction to Treatment - Effects commands Description Also see Description This manual documents commands that use observational data to estimate the effect caused by getting one Treatment instead of another.

8 In observational data, Treatment assignment is not controlled by those who collect the data; thus some common variables affect Treatment assignment and Treatment - specific outcomes. Observational data is sometimes called retrospective data or nonexperimental data, but to avoid confusion, we will always use the term observational data . When all the variables that affect both Treatment assignment and outcomes are observable, the outcomes are said to be conditionally independent of the Treatment , and the teffects estimators may be used. When not all of these variables common to both Treatment assignment and outcomes are observable, the outcomes are not conditionally independent of the Treatment , and etregress or etpoisson may be used.

9 Teffects offers much flexibility in estimators and functional forms for the outcome models and the Treatment -assignment models; see [TE] teffects intro or [TE] teffects intro advanced. etregress and etpoisson offer less flexibility than teffects because more structure must be imposed when conditional independence is not assumed. etregress is for linear outcomes and uses a normal distribution to model Treatment assignment; see [TE] etregress. etpoisson is for count outcomes and uses a normal distribution to model Treatment assignment; see [TE] etpoisson. Endogenous Treatment Effects [TE] etpoisson Poisson regression with endogenous Treatment Effects [TE] etregress Linear regression with endogenous Treatment Effects Treatment Effects [TE] teffects aipw Augmented inverse-probability weighting [TE] teffects ipw Inverse-probability weighting [TE] teffects ipwra Inverse-probability-weighted regression adjustment [TE] teffects nnmatch Nearest-neighbor matching [TE] teffects psmatch Propensity-score matching [TE] teffects ra Regression adjustment Also see [U] What's new [TE] teffects intro Introduction to Treatment Effects for observational data [TE]

10 Teffects intro advanced Advanced introduction to Treatment Effects for observational data [TE] teffects multivalued Multivalued Treatment Effects 1. Title etpoisson Poisson regression with endogenous Treatment Effects Syntax Menu Description Options Remarks and examples Stored results Methods and formulas Reference Also see Syntax . etpoisson depvar indepvars if in weight , . treat(depvart = indepvarst , noconstant offset(varnameo ) ) options options Description Model . treat() equation for Treatment Effects noconstant suppress constant term exposure(varnamee ) include ln(varnamee ) in model with coefficient constrained to 1.