aer-identificationlisted

# AER Identification ## Overview In modern AER-track empirical economics, **identification is the paper**. A weak design cannot be rescued by clever writing, more controls, or a larger sample. This skill walks through the five canonical design-based strategies, the modern defaults that have replaced naive textbook implementations, and the referee-anticipating tests each demands. If the identification strategy is fragile, return to `aer-topic-selection`. There is no point polishing an indefensible empirical strategy. ## When to Use - Designing the empirical strategy for a new project - The current strategy is TWFE / first-stage F / naive RDD and the referee will flag it - A prior submission was rejected on identification grounds and the design needs rebuilding - Choosing between two candidate identification strategies for the same question ## Master Decision Tree ``` Is treatment assignment plausibly random conditional on observables? ├── Yes, by design (RCT, lottery) → run the RCT analysis; register PAP via AEA RCT Registry └── No → identification must come from variation ├── Sharp threshold in a running variable → RDD (sharp or fuzzy) ├── Discrete policy change in some units, not others, over time → DiD │ ├── Single treatment date → canonical 2×2 DiD │ └── Staggered adoption → Callaway-Sant'Anna or Borusyak-Jaravel-Spiess ├── Endogenous regressor + plausibly exogenous shifter → IV │ ├── Shifter × pre-existing exposure shares → shift