First Course Ding: Observational Adjustment (Chapters 11 To 13)

This section groups the observational-study chapters:

• Chapter 11: The Central Role of the Propensity Score
• Chapter 12: Doubly Robust ATE Estimation
• Chapter 13: ATT and Other Estimands

These are the chapters where the current crabbymetrics stack is most different from the original notebooks in a good way. The old third-party weighting and causal packages drop out in favor of:

• Logit
• BalancingWeights
• AIPW
• plain OLS or Ridge nuisance fits when needed

1 What Is Covered

• overlap diagnostics and subclassification
• entropy and quadratic balancing weights
• manual and cross-fit AIPW logic
• ATT versus ATE targeting