This package implements the augmented minimax linear estimator (AML) for estimating
average partial effects, as proposed by Hirshberg and Wager (2017). We consider a
setup where we observe data (X, Y, W) generated according
to a conditionally linear model,
Y = f(X) + W tau(X) + noise
and want to estimate the average effect theta = E[tau(X)] (both W and Y are taken
to be real valued). In the case where W is binary, then theta corresponds to the average
treatment effect under unconfoundedness, and our AML estimator is closely related to approximate
residual balancing as implemented in balanceHD.
To install this package in R, run the following commands:
library(devtools)
install_github("swager/amlinear")Example usage:
library(amlinear)
n = 300; p = 600; nclust = 10
beta = 2 / (1:p) / sqrt(sum(1/(1:p)^2))
clust.alpha = rep(c(0.3, 0.7), nclust/2)
cluster.center = 0.5 * matrix(rnorm(nclust * p), nclust, p)
cluster = sample.int(nclust, n, replace = TRUE)
X = cluster.center[cluster,] + matrix(rnorm(n * p), n, p)
W = rbeta(n, clust.alpha[cluster], 1 - clust.alpha[cluster])
Y = X %*% beta + rnorm(n, 0, 1) + 2 * W * X[,2]
tau.hat = average_partial_effect(X, Y, W)
print(paste("true tau:", round(mean(2 * cluster.center[,2]), 2)))
print(paste("point estimate:", round(tau.hat[1], 2)))
print(paste0("95% CI for tau: (", round(tau.hat[1] - 1.96 * tau.hat[2], 2), ", ", round(tau.hat[1] + 1.96 * tau.hat[2], 2), ")"))
David Hirshberg and Stefan Wager. Augmented Minimax Linear Estimation. 2017. [arxiv]