12.2 Compliers and non-compliers

• Compliers: Exercise if assigned to encouragement, Do not exercise if not assigned to encouragement
• Non-compliers (Angrist, Imbens, and Rubin 1996)
  • Never takers: Do not exercise regardless of instrument (assignment) status
  • Always takers: Exercise regardless of instrument (assignment) status
  • Defiers: Do the opposite of instrument (assignment) status
• Beware: Non-compliance may occur in most seemingly perfect randomized experiments (basic logic very helpful!!)
  • Q: Can you give any examples where/how people may not comply with treatment assignment (e.g., experiment with aspirin, experiment on news consumption etc.)?
  • Q: In that regard what do we understand by “manipulation check”?

References

Angrist, Joshua D, Guido W Imbens, and Donald B Rubin. 1996. “Identification of Causal Effects Using Instrumental Variables.” J. Am. Stat. Assoc. 91 (434): 444–55.