DAG

C

p

E Y

arrow from C to P., C to E, C to Y, P to Y, P to E and E to Y

Use this DAG to answer the following questions

a) Define what constitutes a back door path in a DAG [4 points]. b) Identify all back door paths in this DAG

c) Propose at least one solution for closing each of the identified back door paths

d) State your preferred regression specification and explain why it is your preferred specification

e) Give an example of a plausible confounder which is not yet depicted in the DAG and explain the causal mechanisms involved