Between plurality and proportionality: an analysis of vote transfer systems

TL;DR

This paper introduces a flexible electoral system model combining district and proportional elements, analyzing vote transfer mechanisms, potential manipulation, and applying the model to the 2014 Hungarian election to understand their effects.

Contribution

It develops a general model of mixed electoral systems with vote transfer, exploring trade-offs, manipulation potential, and practical implications through empirical application.

Findings

Trade-off between seat share and majority probability for dominant parties.

Vote transfer rules' effectiveness depends on constituency seat share.

Different vote transfer mechanisms can be functionally equivalent with proper seat allocation.

Abstract

The paper considers a general model of electoral systems combining district-based elections with a compensatory mechanism in order to create any outcome between strictly majoritarian and purely proportional seat allocation. It contains vote transfer and allows for the application of three different correction formulas. Analysis in a two-party system shows that a trade-off exists for the dominant party between its expected seat share and its chance of obtaining majority. Vote transfer rules are also investigated by focusing on the possibility of manipulation. The model is applied to the 2014 Hungarian parliamentary election. Hypothetical results reveal that the vote transfer rule cannot be evaluated in itself, only together with the share of constituency seats. With an appropriate choice of the latter, the three mechanisms may be functionally equivalent.