Why Voters 'Kick Them Out' in Multimember Elections

🧭 Research Puzzle and Argument

Understanding how electoral systems shape representation requires knowing whether voters follow system-specific strategic incentives or stick to simple heuristics. Single-member districts (SMDs) make semi-sincere voting — casting a ballot for the most-preferred party or candidate among the viable options — optimal and commonly observed. In multimember districts (MMDs), that same semi-sincere strategy becomes suboptimal. A formal model shows that, in MMDs, the optimal response is instead to vote to "kick out" the least-preferred party or candidate.

🧾 Evidence From a Lab and a Real Election

Empirical tests use individual-level data on preferences and vote choices across diverse contexts:

• A laboratory experiment run in the United Kingdom that elicits preferences and voting decisions under controlled SMD and MMD conditions
• Individual-level data from a closed-list proportional representation election in Romania

🔑 Key Findings

• Semi-sincere voting is optimal and prevalent in single-member districts.
• In multimember districts, voters shift away from semi-sincere ballots toward behavior consistent with a "kick out" strategy (targeting least-preferred parties or candidates).
• Observed behavior in both the lab and the Romanian election aligns with the predictions of the formal model, indicating that voters adjust strategies in response to the strategic incentives created by electoral rules.

📌 Why It Matters

These results show that electoral institutions actively shape how voters translate preferences into votes. The findings challenge accounts that treat voters as using uniform, system-independent heuristics and underscore the need to model strategic voting as contingent on district magnitude and electoral design.