augment_scm: Augmented Synthetic Control Method (Ridge ASCM)

In coresynth: Fast and Unified Synthetic Control Methods

Augmented Synthetic Control Method (Ridge ASCM)

Description

Applies a ridge-regression-based bias correction to a fitted SCM object, following Ben-Michael, Feller & Rothstein (2021, JASA). The corrected estimator is:

Usage

augment_scm(fit, lambda_ridge = NULL)

Arguments

fit	A coresynth object from scm_fit() with method = "scm".
lambda_ridge	Ridge penalty (non-negative). NULL (default) selects the penalty by leave-one-out cross-validation on the control units.

Details

tau_aug = tau_SCM + (m_tr_post - sum_j W_j * m_j_post)

where m_i_post = Y_pre_i' beta_hat is the ridge outcome model prediction for unit i's mean post-treatment outcome, and beta_hat is estimated by ridge regression across control units.

Value

A list with:

• att_aug: Augmented ATT estimate

• delta: Bias correction term (m_tr_post - sum_j W_j m_j_post)

• att_scm: Original SCM ATT for comparison

• lambda_ridge: Ridge penalty used

• beta_hat: Ridge regression coefficients (length T_pre)

coresynth documentation built on Aug. 28, 2026, 1:06 a.m.