Toggling the Defiers to Relax Monotonicity: The Difference-in-Instrumental-Variables Estimand
通过反向依从行为放松单调性:工具变量差分估计目标
Standard instrumental variables (IV) methods identify a Local Average Treatment Effect under monotonicity, which rules out defiers. In many empirical environments, however, distinct instruments may induce heterogeneous and even opposing behavioral responses. This paper introduces the Difference-in-Instrumental-Variables (DIIV) estimand, which exploits two instruments with opposing compliance patterns to recover a point-identified and behaviorally interpretable causal effect…