A Binary IV Model for Persuasion: Profiling Persuasion Types among Compliers

TL;DR

This paper develops a method using a binary IV model to identify and profile persuasion types among compliers, including voters and non-voters, under certain assumptions, with a test for these assumptions.

Contribution

It introduces a novel approach to identify the joint distribution of potential outcomes among compliers and classify persuasion types using a binary IV model.

Findings

Identifies the joint distribution of potential outcomes among compliers.

Profiles persuasion types: always-voters, never-voters, mobilised voters.

Provides a sharp test for the model's assumptions.

Abstract

In an empirical study of persuasion, researchers often use a binary instrument to encourage individuals to consume information and take some action. We show that, with a binary Imbens-Angrist instrumental variable model and the monotone treatment response assumption, it is possible to identify the joint distribution of potential outcomes among compliers. This is necessary to identify the percentage of mobilised voters and their statistical characteristic defined by the moments of the joint distribution of treatment and covariates. Specifically, we develop a method that enables researchers to identify the statistical characteristic of persuasion types: always-voters, never-voters, and mobilised voters among compliers. These findings extend the kappa weighting results in Abadie (2003). We also provide a sharp test for the two sets of identification assumptions. The test boils down to testing whether there exists a nonnegative solution to a possibly under-determined system of linear equations with known coefficients. An application based on Green et al. (2003) is provided.