Fusion (combination)
Fusion is one of the types of combination techniques for mixed systems and other hybrid multi-member methods. It is an independent type of combination technique.[1]
If a winner-take-all (partisan single winner) system is fused with a proportional system, it is called a bonus system (usually plurality or "majority") bonus.
When fusion is used alongside other combinations, like superposition or coexistence, it is a supermixed system. A jackpot system is a conditional and compensatory sort of variant of the bonus, also by default based on fusion.
Bonus and jackpot
| Size of
bonus (%) |
Size of
jackpot (%) |
Vote share of the
largest party (%) |
Appr. seat share of the largest party (%) | Effective bonus | |
|---|---|---|---|---|---|
| Bonus system | Jackpot system | ||||
| 10% | 45% | 51% | 6% | ||
| 25% | 45% | 59% | 14% | ||
| 50% | 45% | 73% | 28% | ||
| 50% | 45% | 50% | 5% | ||
| 55% | 45% | 55% | 10% | ||
| 60% | 45% | 60% | 15% | ||
| 10% | 55% | 60% | 5% | ||
| 25% | 55% | 66% | 11% | ||
| 50% | 55% | 78% | 23% | ||
| 50% | 55% | 55% | 0% | ||
| 55% | 55% | 55% | 0% | ||
| 60% | 55% | 60% | 5% | ||
- ↑ Massicotte & Blais (1999). "Mixed electoral systems: a conceptual and empirical survey". Electoral Studies. 18 (3): 341–366. doi:10.1016/S0261-3794(98)00063-8.