# Interpretation of the individual effect under treatment spillover

## TL;DR

This paper discusses how to interpret the individual effect of interventions in the presence of spillover effects, which are common in social and health interventions like vaccines and education programs.

## Contribution

It clarifies the interpretation of the individual effect when spillover or dissemination effects are present in networked interventions.

## Key findings

- Provides a causal framework for spillover effects
- Clarifies the interpretation of individual effects in network settings
- Discusses implications for intervention analysis

## Abstract

Some interventions may include important spillover or dissemination effects between study participants. For example, vaccines, cash transfers, and education programs may exert a causal effect on participants beyond those to whom individual treatment is assigned. In a recent paper, Buchanan et al. provide a causal definition of the "individual effect" of an intervention in networks of people who inject drugs. In this short note, we discuss the interpretation of the individual effect when a spillover or dissemination effect exists.