We show that two-stage least squares (2SLS) estimates of interactions can be misleading in settings with essential heterogeneity (e.g., selection into gains) and where complier status to the instrument depends on the interaction variable. The 2SLS estimator cannot disentangle interaction effects...

We show that two-stage least squares (2SLS) estimates of interactions can be misleading in settings with essential heterogeneity (e.g., selection into gains) and where complier status to the instrument depends on the interaction variable. The 2SLS estimator cannot disentangle interaction effects...