  Researchers using instrumental variables to investigate ordered treatments
often recode treatment into an indicator for any exposure. We investigate this
estimand under the assumption that the instruments shift compliers from no
treatment to some but not from some treatment to more. We show that when there
are extensive margin compliers only (EMCO) this estimand captures a weighted
average of treatment effects that can be partially unbundled into each complier
group's potential outcome means. We also establish an equivalence between EMCO
and a two-factor selection model and apply our results to study treatment
heterogeneity in the Oregon Health Insurance Experiment.
