Challenger Quality and the Incumbency Advantage
| DOI | http://doi.org/10.1111/lsq.12109 |
| Published date | 01 February 2016 |
| Date | 01 February 2016 |
| Author | James M. Snyder,Pamela Ban,Elena Llaudet |
PAMELA BAN
ELENA LLAUDET
Harvard University
JAMES M. SNYDER JR.
Harvard University and NBER
Challenger Quality and the
Incumbency Advantage
Most estimates of the incumbency advantage and the electoral benefits of previ-
ous officeholding experience do not account for strategic entry by high-quality
challengers. We address this issue by using term limits as an instrument for challenger
quality. Studying US state legislatures, we find strong evidence of strategic behavior by
experienced challengers. However, we also find that such behavior does not appear to
significantly bias the estimated effect of challenger experience or the estimated incum-
bency advantage. More tentatively, using our estimates, we find that 30–40% of the
incumbency advantage in state legislative races is the result of “scaring off” experienced
challengers.
The incumbency advantage is an important phenomenon in US
politics, but even after years of study, it is not clear what it represents.
Theoretically, scholars have pointed to three main factors: (1) incum-
bents might be of higher “quality” than the average candidate, (2)
holding office might provide resources to incumbents, which they can
use to win votes, and (3) challengers who run against incumbents might
be of lower “quality” than the average politician. Decomposing the
incumbency is important for normative reasons as well as positive rea-
sons. If the incumbency advantage is mainly caused by factor (3)—for
example, because high-quality candidates tend to wait for open seats—
then it may indicate a sub-optimal degree of competition in the electoral
system and possibly a need for reform. On the other hand, if the incum-
bency advantage is mainly due to factor (1)—for example, because on-
the-job learning occurs in politics as in other jobs—then it might reflect a
desirable outcome of a well-functioning electoral system.
Many scholars have attempted to estimate the magnitude of the dif-
ferent components of the incumbency advantage.
1
One reason it is
difficult to estimate the size of component (3) is that it is difficult to
LEGISLATIVE STUDIES QUARTERLY, 41, 1, February 2016 153
DOI: 10.1111/lsq.12109
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C2016 Washington University in St. Louis
estimate the effect of facing a quality challenger in the race, which is one
of the key parameters needed for its estimation.
2
If high-quality chal-
lengers tend to wait until incumbents retire or get into trouble to run for a
seat—e.g., because they are especially strategic in their behavior—then
the observed sample will be skewed toward races where high-quality
challengers face weak incumbents. Similarly, if the challengers who
decide to run against stronger incumbents are mainly low-quality—
because they are less strategic, i.e., less sensitive to their chances of suc-
cess—then again the sample we observe will be skewed toward races
where incumbents face low-quality challengers. In both cases, the behav-
ior will lead to biased estimates both of the effect of challenger quality
on electoral success and the incumbency advantage.
3
This strategic thinking on the part of the potential challengers
seems particularly plausible in light of the fact that one of the best mea-
sures of candidate quality is previous officeholder experience. Intuitively,
many of the strongest candidates are elected officials who hold offices
similar to those they are seeking and with similar constituencies—e.g.,
state legislators running for the US House, state representatives running
for the state senate, or state attorneys general running for governor. Given
that current officeholders face a high opportunity cost of running for
higher office, since they typically must give up their current office in
order to do so, they are probably likely to wait for their odds of success
to be high (e.g., for the incumbent to retire or get in trouble, or for their
party to be strongly favored). Not surprisingly, then, previous empirical
work has found strong evidence of strategic challenger behavior.
4
If high-quality challengers, such as current officeholders, exhibit
strategic entry behavior, then conventional OLS estimates of the incum-
bency advantage may be biased since challenger quality may be
endogenous to the vote. To account for this possibility, we adopt an
alternative approach. We use term limits as an instrument for challenger
quality. Politicians who are term-limited cannot exercise one of their
most popular options—running again for the office they currently
hold—and must either run for a different office or temporarily retire
from politics. As a result, many term-limited candidates run for another
office when they would not otherwise. This yields an exogenous source
of variation in the presence of quality challengers and therefore a plausi-
ble instrument.
5
More specifically, we study state senate elections and measure
challenger quality in terms of previous experience as a state representa-
tive. We then use the number of term-limited state representatives who
reside in a given state senate district as an instrument for the presence of
a high-quality challenger.
6
We find that the instrumental variables (IV)
154 Pamela Ban, Elena Llaudet, and James M. Snyder Jr.
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