Holding office raises the probability of re-election through visibility, resources, constituent service and the deterrence of strong challengers.
The raw re-election rate overstates the effect badly, because the incumbent was the candidate who already beat someone. Careful designs compare near-identical races decided narrowly, and find a genuine but smaller advantage. A substantial part of it is deterrence rather than persuasion: the strongest potential challengers do not stand.
In practice
- A seat that looks safe is safe partly because nobody good contests it, which is an effect and not a cause.
- A supplier up for renewal wins partly because the procurement team would rather not run the tender.
- Possible explanations
- Explanations include name recognition, the resources of office, constituent service, and deterrence, since strong challengers avoid races they expect to lose.
- In its favour
- Designs comparing near-identical races decided by a hair find a real advantage, so the effect survives the obvious selection problem.
- Against it
- The raw re-election rate overstates it badly, part of the measured advantage is selection rather than a benefit of office, and magnitude varies greatly by country, office and era, with some systems showing none.
- Standing
- Magnitude varies greatly by country, office and era, and part of the measured advantage is selection rather than a benefit of office: those who won once were stronger candidates. Estimates fell substantially once designs addressing this were used.
- Subject
- Law & Politics
- Essay
- What can be proved and measured about power