7.3 Simplify

• Too complex: describes everything

• Too simple: does not represent DGP

• Simplify

  • Trivial (e.g. CoffeeShop)
  • Redundancy (e.g. Gender and Race in the DAG)
  • Mediators: if variable exists only as a way for one variable to affect another (e.g. Preferences)
  • Irrelevance: if variable isn’t on any path between treatment and outcome