Lecture 17 Causal Diagram Practice
March 3, 2019
- To make a diagram:
- List all the relevant variables
- Combine identical variables, eliminate unimportant ones
- Draw arrows to indicate what you think causes what
- (See if the model implies that any relationships SHOULDN’T exist and test that)
- Think carefully!
- If we’re interested in the effect of
- Write the list of all paths from
- Figure out which are front-door paths (going from
- and which are back-door paths (other ways)
- Then figure out what set of variables need to be controlled/adjusted for to close those back doors
- Just a little more detail on this “testing relationships” thing
- Our use of front-door and back-door paths means that we can look at any two variables in our diagram and say “hmm, if I control for A, B, and C, then that closes all front and back door paths between D and E”
- So, if we control for A, B, and C, then D and E should be unrelated!
cor(D,E) controlling for A, B, C is big, our diagram is probably wrong!
- What are some relationships we can test?