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1/n
Tired of caricatures? Note that we never construct a dag by listing 150,ooo variables. We start by asking: can you think of a variable affecting both X and Y? Is it measured? If not, is it significant? If yes, lump it together with all other such variables and mark it U,
Tired of caricatures? Note that we never construct a dag by listing 150,ooo variables. We start by asking: can you think of a variable affecting both X and Y? Is it measured? If not, is it significant? If yes, lump it together with all other such variables and mark it U,
2/n
"unobserved confounders", ONE node. Next you ask: Can you think of a variables that is either (1) on the X-Y path and shielded from U, or (2) affects
X and is sheilded from U and not affecting Y (except..)? The former is front-door the latter is IV. And so on and on. At each
"unobserved confounders", ONE node. Next you ask: Can you think of a variables that is either (1) on the X-Y path and shielded from U, or (2) affects
X and is sheilded from U and not affecting Y (except..)? The former is front-door the latter is IV. And so on and on. At each
3/n
stage the question arises: What is "shielded"? and the answer is given, again, in term of: "Can you think of a variable that resides here or there...and has a property that can easily be verified in the "mind's DAG" which is expert in answering only one primitive question:
stage the question arises: What is "shielded"? and the answer is given, again, in term of: "Can you think of a variable that resides here or there...and has a property that can easily be verified in the "mind's DAG" which is expert in answering only one primitive question:
4/5
"Who is listening to whom?". Caricatures are not helpful. Note that you need the "mind's DAG" to certify any candidate IV. Note also that you need the theory of identification to interrogate your mind's DAG toward identification templates, eg. backdoor, frontdoor`, IV, ..
"Who is listening to whom?". Caricatures are not helpful. Note that you need the "mind's DAG" to certify any candidate IV. Note also that you need the theory of identification to interrogate your mind's DAG toward identification templates, eg. backdoor, frontdoor`, IV, ..
5/5
conditional IV, etc. etc. Finally, once you construct the DAG in this incremental way, guided by hoped-for identification templates you may end up with 4-10 variables, and become uncertain of identification -- go to do calculus, the ultimate arbiter (for NP). #Bookofwhy
conditional IV, etc. etc. Finally, once you construct the DAG in this incremental way, guided by hoped-for identification templates you may end up with 4-10 variables, and become uncertain of identification -- go to do calculus, the ultimate arbiter (for NP). #Bookofwhy
