Lost in Aggregation: The Causal Interpretation of the IV Estimand
arXiv:2601.12120v1 Announce Type: cross Abstract: Instrumental variable based estimation of a causal effect has emerged as a standard approach to mitigate confounding bias in the social sciences and epidemiology, where conducting randomized experiments can be too costly or impossible. However, justifying the validity of the instrument often poses a significant challenge. In this work, we highlight a problem generally neglected in arguments for instrumental variable validity: the presence of an ”aggregate treatment variable”, where the treatment (e.g., education, […]