One Instrument to Rule Them All: The Bias and Coverage of Just-ID IV

@inproceedings{Angrist2021OneIT,
  title={One Instrument to Rule Them All: The Bias and Coverage of Just-ID IV},
  author={Joshua David Angrist and M. Koles{\'a}r},
  year={2021}
}
Two-stage least squares estimates in heavily over-identified instrumental variables (IV) models can be misleadingly close to the corresponding ordinary least squares (OLS) estimates when many instruments are weak. Just-identified (just-ID) IV estimates using a single instrument are also biased, but the importance of weak-instrument bias in just-ID IV applications remains contentious. We argue that in microeconometric applications, just-ID IV estimators can typically be treated as all but… 

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