Machine Learning, Causal Inference, Meta Learning, Instruments, Observational Studies.
and Dⱼ⁰ for user j in the control groups based on μ₁(x): Then estimate τ₁(x) = E[ D₁ ∣ X = x ] and τ₀(x) = E[ D₀ ∣ X = x ] using machine learning models. Stage 3: Define the CATE estimate by a weighted average of μ₁(x) and μ₀(x): where g ∈ [0,1] is a weighting function. X-learner uses a weighting