Winning advantage

• Department of Political and Social Sciences

This session of the Political Behaviour Colloquium features a presentation by Ioannis Mastrominas, a PhD Researcher at EUI

Winning an election is not merely an outcome — it is an input into future behavior. A large literature documents the incumbency advantage, yet struggles to separate the behavioral consequences of winning itself from the material privileges of holding office. We argue that electoral victory shapes politicians' confidence in their own prospects, increasing their willingness to seek re-election and invest effort in subsequent campaigns. To isolate this mechanism, we exploit a particularly demanding test: rather than comparing winners to losers, we compare two types of winners who hold the same office but differ in how they obtained it. Using data from five Greek parliamentary elections (2007–2019) and a within-party-list Regression Discontinuity design, we compare Members of Parliament who won "regular" seats through personal votes with those who entered parliament through institutionally allocated bonus seats. Despite serving in the same parliament and receiving nearly identical vote totals, regular MPs — whose victory is more attributable to personal performance — are significantly more likely to run in the subsequent election and to be re-elected. We find no evidence that parties differentially promote regular MPs or that voters can distinguish between the two types. These findings point to politicians' own beliefs about their competence as the operative mechanism. Since even variation in how victory is experienced produces behavioral divergence among incumbents, the confidence gap between winners and losers — where the experiential contrast is far greater — is likely at least as consequential. Our study identifies a behavioral microfoundation of incumbency advantage: winning itself, and how it is interpreted, durably shapes political careers. 

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