Testability of Instrumental Variables in Additive Nonlinear, Non-Constant Effects Models

ArXi:2411.12184v2 Announce Type: replace-cross We address the issue of the testability of instrumental variables derived from observational data. Most existing testable implications are centered on scenarios where the treatment is a discrete variable, e.g., instrumental inequality (Pearl, 1995), or where the effect is assumed to be constant, e.g., instrumental variables condition based on the principle of independent mechanisms (Burauel, 2023