9.5 Riding a Shooting Star

Front Door Method: when a back-door path has a variable that cannot be measured

• Measure both

\[\text{Treatment} \rightarrow M \text{ and } M \rightarrow \text{Outcome}\]

• Can then measure

\[\text{Treatment} \rightarrow M \rightarrow \text{Outcome}\]

• But \(M\) cannot be related to other DAG variables