| Abstract: | This paper estimates the incumbency effects in elections to the House of Representatives of 45 states in the United States using a quasi‐experimental research method, regression discontinuity design (RDD). This design isolates the causal effect of incumbency from other contemporaneous factors, such as candidate quality, by comparing incumbents and non‐incumbents in close contests. I find that incumbents in state legislative elections have a significant advantage, and this advantage serves as a strong barrier to re‐entry of challengers who had previously been defeated. However, the incumbency advantage estimated using the RDD is much smaller than are the estimates using existing methods, implying a significant selection bias in the latter. |
