In the last years there has been a decrease of voter turnout in most of
the European countries. Factors influencing voter turnout are many and
among them there are economic factors such as costs related to the act of
voting; demographic factors such as the individual characteristics of voters;
technological and institutional factors and so on. Low turnout has among its
consequences an unfair representation of the population and therefore, it is
usually considered to be a socially unwanted outcome. Consequently, there have
been numerous studies which aim was to identify the determinant factors of
turnout, in order to encourage participation in the political process. Despite
significant study into the matter, the causes and consequences for the changes
in voting turnout are still not clearly determined.
In his work Jackman
(1987) finds that political institutions and electoral law have an important
impact on voter turnout. He
shows that electoral districts which are more competitive at national level,
foster voter turnout. He also finds that Multipartyism decreases turnout,
since it weakens the relevance of elections in the formation of a government.
Among these causes, of relevant
importance is the impact of the electoral system on voter turnout.
Blais and Carty
(1990) assess the effect of different electoral formulae on voter turnout in
western democratic states and find higher turnout rates in states adopting the PR
Several empirical studies have attempted to explain
the consequence of having more freedom on the choice of a candidate on voter
turnout. Among them, there are several
papers about the effect of Open List vs. Closed List, with dissimilar views on
their impact on voter turnout.
at al (2014) find that open list systems allow for intra-party competition which
permit voters to choose among not only parties but also among candidates,
fostering competition among candidates and allowing for smaller parties to get
more representative power.
In contrast, Robbins (2010) find that party-centered
closed list systems compared to candidate-centered open list systems, increase
voter turnout. This is a consequence of the more active lobbying activities of
parties in closed list systems, which aim is to have a higher influence on
voters’ preferences. In
general, the empirical evidence is unsettled and the effect of the poll
structure on turnout is still an unsolved query.
Sanz (2015) studies
the effect of electoral system on voter turnout in Spain. He compares voter
turnout among municipalities with
different electoral systems as well as different number of citizens. He shows
that open list systems compared to a closed list system enhances voter turnout,
as a consequence of the possibility given to voters to choose for individual
candidates from the same or different party list.
On the same line, with the present work the aim is
to assess the impact of electoral system on voter turnout in Italy. I will make
use of the particular institutional framework of Italian local elections where
municipalities are divided into two main groups, namely those that apply the
single ballot plurality system and those that apply instead dual ballot
majority system. I will then assess the impact of these two different rules on
voter turnout by means of regression discontinuity design.
Hence, the present work aims to contribute to the
already existing collection of works, hoping to put more light on the
consequences that the freedom of choice of voters has on turnout. Moreover, to
my knowledge there are no other studies which use the RD design to estimate the
impact of the two electoral systems on voters’ casting choice and consequently
voter turnout of Italian municipalities.
Electoral system in Italy
administrative divisions in Italy are: Regions, Provinces and Municipalities.
Municipalities are autonomous and independent administrative divisions. They
are included in the Province. However, they can entertain direct relations with
the regions and the State due their autonomy. As of February 2017, there were
7,981 municipalities in Italy. The political organs of a municipality include municipal
council (a legislative body) and the municipal committee (an executive body),
both organs assist the mayor. Elections are held every five years.
the implementation of the law n.81 of 1993, the mayor is directly elected by
citizens which happens simultaneously with the election of the municipal
council. Moreover, such law requires that municipalities are subject to two
different electoral rules, according to their population size.
with a population of less than 15000 residents apply the single ballot plurality
system. Residents in this category
vote for both the municipal council members and the mayor. Voting for a mayoral
candidate means voting also for the list supporting the candidate. It will be
elected mayor the candidate that gets the plurality of votes. The election
takes place in a single round, except for the eventuality in which the two most
voted candidates have obtained the same number of votes. In this case, the
second ballot will proceed and if a further parity were to be registered, it
will be elected the eldest one among them. The list of the elected mayor will
get a two-thirds majority of the seats in the municipal council, whereas
one-third of the seats will be proportionally distributed among the defeated
the other hand, municipalities with a population of more than 15000 residents
apply the dual ballot majority election rule. If no candidate has the
majority of votes (i.e. more than half) in the first round, then only the two
candidates with the most votes proceed to a second round (called “closed
ballot”), which will be held two weeks later. In the second ballot, because
there are only two candidates, one candidate will attain with certainty a
majority. In this category, each candidate is supported by
one or more lists. Besides that, each
voter is entirely free to change the candidate he votes for, even if his
preferred candidate has not yet been eliminated but he has simply changed his
mind (called “panachange vote” or “disjoint vote”). The “panachange
vote” allows citizens of municipalities with more than 15000 residents to
vote, in the first round, in three possible ways:
can vote for a list. By voting a list they also vote the candidate associated
to that list.
can vote for a list and they can specify two candidates of that list, provided
they are of opposite sex.
can vote a candidate. By voting this way, their vote is valid only for the
candidate and not for the list or lists supporting the candidate.
the second round, voters can vote only between the two most voted mayoral
candidates and cannot vote for any list. The two candidates can choose to be
supported by a different list than the one they were initially supported by.
The winner is the candidate that gets the majority of votes. Once the winners
are announced, seats will be assigned to each list or group of lists with the
proportional d’Hondt method.
municipal council is elected in a single round with a complex system that we
can define as mixed in some specific cases, while it can be proportional in
others. In the former case it is called a “mixed system”, since it can be
partly proportional and partly majoritarian. More precisely, we can have the following
is elected in the first round (by majority), however the list or lists
supporting the candidate do not reach the 50% of votes. In this case seats are
assigned in a proportional way.
is elected in the first ballot by majority, but the list or lists supporting
the mayor gets 40% of votes and no other list gets more than 50% of votes. In
this case the list supporting the mayor gets 60% of the seats in the council
and the remaining seats are assigned proportionally.
is elected in the second ballot (by plurality), but the list supporting the
mayor already got in the first ballot 40% of the votes and no other list got
more 50% of votes. Also in this case, the list supporting the mayor gets 60% of
seats and the remaining seats are assigned proportionally. Lists that have not
achieved at least 3% of votes are not assigned any seats.
An important thing to keep in mind, is that the
preference vote was maintained in both municipality groups. Moreover, in both
cases, expressing a unique preference allows the voter to change the order of
the candidates in the list and to establish their ranking. The main difference
between larger and smaller municipalities, is therefore, the possibility of
expressing a disjoint vote in the
Data and Methodology
In order to estimate the causal effect of the two
electoral rules on voter turnout, I will make use of a rich data set from the
official interior ministry site, with results from all elections since the
implementation of the national rule (data available from 1993 to 2017). The
data set contains detailed information on candidates and voters in each
election year, both at the aggregate level and at the municipality-individual
level (number of electors and of voters, number of invalid votes, sex of voters
and candidates, etc).
Moreover, I will use publicly available data from
the National Statistics Institute (ISTAT). ISTAT attributes to each existing
municipality a six-digit code. The first three digits of the code identify the
province to which the municipality belongs, while the subsequent three identify
the municipality within the province. Following each administrative change, the
list of Italian municipalities and their codes is updated. It also takes care
of an archive containing the list of the existing municipalities, the list of
deleted municipalities, the territorial and administrative changes of the
municipalities since 1991 and a table of codes and names of geographical areas,
regions and provinces.
To assess the impact of the electoral system on
voter turnout I will exploit the regression discontinuity design.
The control group will be represented by the
municipalities with a population less than 15000, while the treatment group
will be represented by the municipalities with a population higher than 15000. Moreover,
I will add to the basic equation municipality and year fixed effects.
Hence, we can let the value of the unobserved
variables be different in the treatment and in the control group, as long as
they remain fixed over time and at individual level. Error terms will be
clustered at municipality level.
Thanks to its peculiarities, the Italian
institutional context of local elections enables to trustfully identify the
differences in outcomes between treatment and control group, as the causal
effect of the electoral system. Meaning, the number of municipalities and the
years of all elections since the adoption of the national law are high (data
about elections available from 1993 to 2017). Accordingly, the number of
observations will also be high which will lead to increased precision
in estimates. Moreover, both groups
of municipalities will differ only in their electoral rules at the threshold. Additionally,
I will restrict my analysis to only those municipalities where elections did
not have a second ballot, for several reasons.
First, as a consequence of the different nature of
the two electoral systems, the control group and the treatment group will have
different probabilities to proceed to the second turn of elections. Therefore,
the estimates will be more precise if we only compare municipalities similar with
respect to the prior probability of having a second turn of elections. But,
knowing this, candidates would behave differently if they were in a
municipality with risk of run-off, regardless of the electorate’s inclination. For
example, smaller party lists may decide to present themselves with their own
candidate and measure their consent in the first round, significantly fragmenting
the electoral offer. Eventually, in a second moment, they could form a
coalition with one of the two competitors for the run-off, in order to also
enjoy the eventual majority prize. On the other hand, voters themselves
can set up strategic behaviors, casting their vote only for the candidate-mayor
with higher possibility of victory and not for the list supporting that
candidate (disjoint vote).
In both cases, estimates would be biased.
Therefore, by considering exclusively municipalities with no second ballot
elections, we reduce such biases.
should not be possible to precisely manipulate the assignment variable,
otherwise the RD design will not be the right approach to follow. Lee and
Lemieux (2010) suggested different methods to test the assumptions of the RD
design which I will now discuss. A
way to test the imprecision of control over the assignment variable is to
examine its density. We should have no jump in the density at the cut-off,
otherwise there may be sorting around the threshold, which invalidates the
suitability of the RD design. We could also examine if the treatment and the
control group are similar conditional on observable variables, most of which
should be the same. Finally, we could implement a falsification test and assume
to find continuity in predetermined variables at the treatment cut-off. Since
these variables were determined before the treatment decision, treatment status
should have no effect on them. If the predetermined variables show a
discontinuity at the treatment cut-off or in other points, we should not be
confident about the accuracy of our results and look at the RD design sceptically.
Another problem might be that of
endogeneity. However, as already said, being municipalities subject to the
implementation of different electoral systems as a consequence of having a
different number of inhabitants in their territory, reduces considerably the
problem of endogeneity, moreover since this rule derives from a national law. As
we know, another key issue when using RD design is the choice of the bandwidth,
since both precision and bias increase as the portion of bandwidth considered
increases. In order to choose the most appropriate bandwidth, we can provide
results for different measures of it and see how sensitive the results are to these
different adoptions (Lee and Lemieux, 2010).
The biggest limitation of this approach is that
only municipalities with single-ballot elections will be considered in the
analysis. This implies a restriction in the number of observations, but more
importantly, it could mean that we are only considering those municipalities
where voters are less indifferent to certain choices than to others.
This together with the possibility of strategic
behavior of candidates and voters, as already discussed, would bias our