The basics I – matching
In this section, we’ll discuss the basics of matching. We’ll introduce ATE, ATT, and ATC. We’ll define a basic matching estimator and implement an (approximate) matching estimator using DoWhy’s four-step causal process.
Matching is a family of methods for estimating causal effects by matching similar observations (or units) in the treatment and non-treatment groups. The goal of matching is to make comparisons between similar units in order to achieve as precise an estimate of the true causal effect as possible.
Some authors, including Stuart (2010) and Sizemore & Alkurdi (2019), suggest that matching should be treated as a data preprocessing step, on top of which any estimator can be used. This view is also emphasized by Andrew Gelman and Jennifer Hill: “Matching refers to a variety of procedures that restrict and reorganize the original sample” (Gelman & Hill, 2006).
If you have enough data to...