Difference In Difference, Observational Studies, Causal Inference, Instrumental Variable, Regression.
is implemented, T and C groups show parallel trends. The effects of any covariates on the T and C groups are always the same. Outcome = β1 * Treatment_period + β2 * Treatment_group + β3 * Treatment_period * Treatment_Group + C β1: estimates the effect on the Y variable in the treatment period from