The Toolkit for Weighting and Analysis of Nonequivalent Groups, or TWANG, contains a set of functions to support causal modeling of observational data through the estimation and evaluation of propensity score weights. The TWANG package was first developed in 2004 by RAND researchers for the R statistical computing language and environment. The R version of the package contains functions for creating high-quality propensity score weights which can be used to estimate treatment effects with two or more treatment groups.
In 2014, TWANG macros were developed for SAS to support the use of these tools without requiring researchers and analysts to learn R. At this time, the SAS TWANG macros can support estimation of propensity scores and their associated weights for comparisons involving two treatment groups. SAS macros will be made available shortly for handling the case of three or more treatment groups.
This tool includes the TWANG macros for SAS, a tutorial on their use, and the sample code and datasets used in the tutorial.
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