Ignorability and stability assumptions in neighborhood effects research. Stat Med

Two central assumptions concerning causal inference in the potential outcomes frame-work for estimating neighborhood e¤ects are examined. The stable unit treatment value assumption in the context of neighborhood e¤ects requires that an individ-uals outcome does not depend on the treatment assigned to neighborhoods other than the individuals own neighborhood. The assumption is important in that it makes estimation feasible; although some progress can be made even when the as-sumption is relaxed. Some discussion is given concerning the contexts in which the neighborhood-level stable unit treatment value assumption is likely to hold. The ignorability assumption allows the researcher to move from conclusions about as-sociation to conclusions about causation. In the context of neighborhood-wide in-terventions, the ignorability assumption for the individual-level potential outcomes framework can be easily adapted for neighborhood e¤ects