4.15 ATE: Average Treatment Effect

• Average Treatement Effect: The average difference in the pair of potential outcomes averaged over the entire population of interest (at a particular moment in time)
  • ATE = E[Y_i1 - Y_i0]
  • Time is omitted from the notation
  • Q: Which observations does that concern in the table below?¹⁸

Unit	Di (Aspirin: Yes/No)	Yi1 (Pain | Aspirin)	Yi0 (Pain | NoAspirin)
Simone	1	0	?
Julia	1	1	?
Paul	0	?	1
Trump	0	?	0
Fabrizio	0	?	0
Diego	0	?	0

• Again.. can’t estimate ATE without observing both potential outcomes (Even with infinite sample size)

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18. All…↩