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Strategic voting in mixed-member electoral systems: The Italian case

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Strategic voting in mixed-member electoral systems: The Italian case
Strategic voting in mixed-member electoral systems:
The Italian case*
Kenneth Benoit
Trinity College
[email protected]
Daniela Giannetti
University of Bologna
[email protected]
Michael Laver
Trinity College
[email protected]
August 24, 2000
Abstract:
The new Italian electoral system has two elements, a plurality element in single
member districts and a PR element in larger multimember constituencies. The
plurality element provides strong incentives for groups of parties to form pre-electoral
coalitions. The PR element offers incentives for parties to contest the elections
individually. We can think of two types of voter. The first type, whom we
characterize as “strategic,” votes for his or her first choice party in the PR election
since there is no strategy that can improve on this. In the plurality election, a strategic
voter supports the candidate sponsored by the coalition with which his or her first
choice party is affiliated, even if this is not from the first choice party. The second
type of voter, whom we characterize as “non-strategic,” also votes for his or her first
choice party in the PR election. In the plurality election, the non-strategic voter will
vote for a first choice party if a candidate of this party is on the ballot but, if not,
votes unpredictably. In this paper, we model the “strategic” and “non- strategic”
elements of the vote flowing to candidates in the plurality element of the election.
Using data from the 1996 and 1994 elections on both PR and plurality voting patterns
in each single member district, and confining ourselves to districts where there is a
run-off between two coalitions, we are able to estimate the relative numbers of
strategic and non- strategic voters in each district, and characterize this in terms of a
range of strategic variables.
*
Prepared for delivery at the 2000 Annual Meeting of the American Political Science Association,
Mariott Wardman Park August 31-September 3, 2000. Copyright of the American Political Science
Association. Despite the official APSA policy we would be pleased if you contact us prior to citing
since this paper is a work in progress. Thanks to Raj Chari for help with several of the equations and
to John Haslett and David Jackson for comments.
1
1 Introduction
It has been appreciated for as long as there have been elections that the act of voting
confronts voters with problems of strategic choice. (See Farquarson 1969, for an
analysis of ancient strategic voting examples.) It has also been understood for a long
time that different voting systems confront voters with different problems of strategic
choice. (For the seminal review of this field see Cox 1997). Perhaps most notoriously,
when the plurality electoral system operates in an environment with more than two
parties, voters risk wasting their votes if they do not think strategically. In a threecandidate contest, for example, a voter who prefers the candidates in the order (A, B,
C) and knows that candidate A is forecast to get the least votes must consider voting
strategically for B in order to improve B’s chances of beating C, the voter’s leastpreferred candidate. Thus vote totals for third and lower candidates in plurality
constituencies will understate these candidates’ levels of “true” support to the extent
that “strategic” supporters have shifted their votes to other candidates with better
chances of winning. For the same reasons, vote totals for the winning and runner-up
candidates will overstate their level of “true” support to the extent that these
candidates have benefited from strategic defections from supporters of other
candidates.
An extensive formal analysis of this phenomenon has been carried out by Cox (1997,
69-98). In a model with very strong assumptions, strategic voting reduces any
plurality election to a contest between the top two candidates, since supporters of
other candidates find it rational to defect from their first preference candidate and use
their votes to influence this contest rather than “wasting” their votes on candidates
who will in the end not get elected. Cox (1997, 76-78) identifies four key assumptions
generating this strong (and empirically implausible) result.
First, not all voters may have strict preference orderings over the candidates. Some
may be indifferent between two or more candidates. In our simple example above, if
the supporter of candidate A is indifferent between B and C, he or she has no
incentive to vote strategically. Cox calls such a voter part of A’s “hard-core” support
– the group of voters who do not care which of the electable candidates wins, if A
does not win. To the extent that a candidate has hard core supporters in this sense, he
or she will get votes even if not on of the top two candidates.
Second, the distribution of preferences in the electorate may be such that there is a
Condorcet winner in the election (i.e. one who can beat very other candidate in a
pairwise runoff). Cox notes that this situation presents no incentive for strategic
voting, and voters may as well continue to support their first-preference candidate.
Third, voters must be myopic in the sense of only considering the result of the current
election. If, for example, voters are motivated to support some candidate in order to
increase his or support with a view to building an expectation of success in future
elections, this motivation may well undermine the incentive to vote strategically.
Fourth, as Cox points out, there may well not be common knowledge about the
various candidates’ probabilities of being successful. To the extent that voters have
2
different views about these probabilities, they may engage in different strategic
calculations and not all concentrate their votes on the top two candidates.
Thus strategic voting leading to two-candidate competition in plurality elections is the
limiting case. In more realistic environments, it seems likely that some but not all of
the voters who have an incentive to do so will vote strategically in plurality elections.
This will lead to an increase in the level of support for front-running candidates and a
reduction in the level of support for trailing candidates. The result will be a
defragmentation of patterns of candidate support in the election and a consequent
reduction in the effective number of parties.
The incentives for strategic voting extend well-beyond the simple plurality electoral
system. A particularly interesting set of cases concerns variants of the “mixed”
electoral system, in which voters simultaneously cast two ballots – one in a plurality
election to single seat constituencies, and one in a list-PR election to larger multi-seat
constituencies. Originally introduced in 1949 for Germany, versions of this system
have now been adopted in Italy, Japan, and New Zealand. The interest arises because
the list-PR element of the election provides incentives for non-strategic voting, while
the plurality election provides incentives for strategic voting.1 This opens up the
possibility of trying to estimate the level of strategic voting in the plurality element of
such an election. Cox (1997, 82-83) explores this by testing the proposition that
German voters should desert less successful candidates more frequently in plurality
constituencies where the gap between the first and second ranked plurality candidates
is narrower, and find systematic evidence that this does in fact happen.
Despite the clear logical incentives for strategic voting in mixed electoral systems,
there has been little research that goes beyond the German case. In all cases,
furthermore, actual empirical levels of strategic voting can in practice be very difficult
to estimate systematically. In particular, estimating levels of strategic voting behavior
from aggregate voting data has presented difficult methodological problems of
ecological inference.
However new techniques of ecological inference offer the possibility of estimating
levels of strategic voting in “mixed-member” electoral systems. The purpose of this
paper is to apply these techniques to the analysis of aggregate voting data in recent
Italian elections operating under a mixed-member system. Our aim is to use aggregate
voting data to estimate levels of strategic voting in Italy.
The plurality element of Italian elections provides strong incentives for groups of
parties to form pre-electoral coalitions, for precisely the reasons elaborated by Cox
and discussed above. Within these coalitions, parties agree to sponsor a single
“coalition” candidate in the plurality election rather than engage in self-destructive
competition with each other. Each party within each coalition still, however, has a
strong incentive to present its own list in the PR element of the election. This situation
presents Italian voters with some important strategic choices. Very generally
speaking, we can think of two types of voter. The first type of voter, who we
characterize as “strategic”, votes for his or her first choice party in the PR election
1
There may, however, be incentives for strategic voting in the list-PR element of German elections, if
supporters of a larger party wish to keep a potential weaker coalition partner above the five percent
size threshold for the PR election.
3
since there is no strategy that can improve on this. In the plurality election, which
typically reduces to well-forecast competition between two coalitions with very few
“open” three-way contests, a strategic voter supports the candidate on the ballot
sponsored by the coalition with which his or her first choice party is affiliated, even if
this is not from the first choice party, for reasons we elaborate below. The second type
of voter, who we characterize as “non-strategic”, also votes for his or her first choice
party in the PR election. In the plurality election, the non-strategic voter votes for the
first choice party if this has a candidate on the ballot. If the first choice party is not on
the ballot in the plurality election, then the strategic voter behaves unpredictably. (We
observe that almost all voters do in fact vote in both elections.)
Because all Italian parties put forward their own PR candidates but support plurality
candidates belonging to mutually exclusive blocs or “cartels”, we have a chance to
observe cross-over voting and strategic voting by comparing aggregate votes between
types of ballot in each district. In this paper, we use the PR element of the election as
an expression of sincere voter preferences and model the “strategic” and “nonstrategic” elements of the vote flowing to candidates in the more strategic plurality
element of the election. Using data on PR and plurality voting patterns in each single
member district where there is a run-off between two coalitions we estimate, using
King’s (1997) ecological inference technique, the relative numbers of strategic and
non-strategic voters in each district, and characterize this in terms of a range of
variables.
The next section looks in more detail at the strategic incentives confronting Italian
voters. Section 3 develops a formal model of possible patterns of strategic behavior in
Italy, expressed in terms of quantities that can be observed or estimated from
aggregate data on Italian voting behavior. Section 4 applies King’s ecological
inference technique to the estimation, from aggregate voting data, of levels of
strategic voting in each Italian single-member district. Section 5 explores patterns of
systematic variation in levels of strategic voting.
2 The incentives for strategic voting under the Italian mixedmember electoral system
Italian lower chamber elections are divided into 475 single-member districts in which
candidates compete in plurality elections, as well as 26 multimember proportional
representation (PR) constituencies (circoscrizioni). Each PR constituency boundary
completely contains its component single-member districts (SMDs).2 In all, 475 seats
are allocated under plurality rules and 155 by proportional representation (PR), giving
a total legislature of 630 seats.3 This electoral system was approved by the Italian
Parliament on August 1993, and was expected by many to bring about profound
structural change in the party system, and especially a significant reduction in the
number of parties. This is because the dominant plurality element in the electoral
2
There is also a 27th constituency (the smallest region Val D’Aosta) containing a lone SMD but having
no PR seats.
3
The number of PR seats a party will eventually obtain is determined by subtracting the plurality vote
share of second placed candidates in the districts where a party has won a seat from the PR vote share
of that party at the constituency level. This is a “partial deduction,” known as the scorporo.
4
system was expected to provide strong incentives for parties to combine into larger
units, so as to avoid the damaging effects of splitting the available vote between them.
(For a brief but clear description of these systems, see D’Alimonte 1998.)
In the event, things did not work out this way and Italy has remained very much a
multi-party system. While the plurality element of the system did force groups of
parties to band together to form electoral cartels, the proportional element of each
election gives a very clear indication of the relative strength of individual members of
the cartel. This information proved to be crucial in the allocation of cabinet positions
between members of the cartel that found itself in a position to take over the
government. This factor was compounded by pressures generated by what were
inevitably closely fought contests between the parties within each cartel over the
allocation, in subsequent elections, of candidatures in the single-member
constituencies.
Nonetheless the dominant plurality element in the Italian electoral system has
certainly generated a form of majoritarian electoral competition in the single-member
districts. Thus recent electoral competition has been structured around two major
electoral coalitions, the Polo della Libertà and the Ulivo. There has also been a
tendency for these electoral coalitions to present themselves to voters as potential
governments. During the 1996 election campaign, for example, the names of the
would-be Prime Ministers and their governmental programs were clearly indicated by
the two main electoral coalitions.
Voters therefore may vote sincerely for their most preferred party on the list ballot,
since nearly every party establishes a list. With the plurality ballot, however, voters
face a possibly strategic choice, depending on the nature of the voter and on the party
which the cartel has agreed will sponsor the exclusive plurality candidate for that
cartel. In the next section we develop a more formal model of this voter choice in the
plurality voting.
3 A Model of Voting in the Italian System
The conflicting electoral pressures between ballot types have confronted Italian voters
with some important strategic decisions. The PR element in the election provides
strong incentives for voters to vote “sincerely” for their most-preferred party. It is
difficult to see any incentive for them to do otherwise since, given the way that
5
Some voters may not switch votes in this way. This may be because they are rational
voters who are not focused on policy implementation by likely governments and are
unwilling to make the policy compromises necessary in order to get their mostpreferred party into power – for example because they wish to promote a particular
policy position in the wider political arena and do not like the idea of adding to the
ostensible support of a party promoting policies with which they disagree. (Maybe
some non-cartel party is promoting policies closer to those of their most-preferred
party, for example). It may also be because the voter concerned is not rational in the
6
Cu The sum of the list vote (at the district level) for all parties in the L’Ulivo cartel.
Cp The sum of the list vote (at the district level) for all parties in the Polo cartel.
Co The sum of the list vote (at the district level) for all parties in neither L’Ulivo nor Polo
cartels, defined as (V - Cu - Cp).
Given the general argument in the preceding section, our basic model of voter
behavior is as follows.
1. Party-based preference: Each voter has a sincere preference for one of the
political parties that is contesting the list-PR element of the election.
2. List Vote: Each voter’s list vote is a sincere expression of this preference.
3. SMD Vote: Voters will cast their candidate-based ballots in the following
manner:
(a) Loyally, for the candidate of their preferred party, if that party has a
candidate in the SMD. This implies that Pi ≥ Li.5
(b) If the voter’s preferred party does not have a candidate in the SMD, then
voters will behave in one of two ways:
i.
Strategically: the voter will vote for the candidate sponsored by
the cartel to which his/her preferred party belongs, represented as
Rp, Ru, and Ro denoting the total number of strategic voters
whose preferred party is in the Polo, Ulivo, and Other cartels
respectively.
ii.
Non-strategically: the voter will choose a candidate of a party
sponsored by a cartel other than the one to which his/her preferred
party belongs.
Cartel Plurality Vote
Cartel List Vote
Cp
Cu
Co
Voter Type
Loyalists
Strategic
Non-Strategic
Loyalists
Strategic
Non-Strategic
Loyalists
Strategic
Non-Strategic
Pp
Lp
Rp
0
-0
Nup
-0
Nop
Pu
-0
Npu
Lu
Ru
0
-0
Nou
Po
-0
Npo
-0
Npo
Lo
Ro
0
Table 1: Composition of Plurality Vote P and Cartel Vote C in a SMD
5
I’ve tested this and it works everywhere, although I will document the fact precisely here.
7
From these assumptions we can model the composition of the candidate vote in a
single-member district (Table 1). In each SMD the total number of votes V is
partitioned by both the list ballots for cartel parties (Cp, Cu, and Co) and by the
candidate ballots for cartel parties (Pp, Pu, and Po). According to assumption 3a, any
intersection of (Ci,Pi) will contain Li, since all voters whose preferred party has a
candidate will vote loyally for that candidate in the SMD. The intersection (Ci,Pi) will
also contain the strategic voters Ri preferring a party in cartel i who have voted for a
candidate from a party of the same cartel. The remainder of the plurality vote Pi will
consist of non-strategic voters who, not having found a candidate from their most
preferred party in the SMD, will have voted for cartel i candidate instead. These
quantities are denoted as Eup and Eop for the voters preferring a party in cartel u and o
respectively, who cast their ballots for the Polo cartel candidate.
Note that in Table 1, a zero (“0”) indicates that the quantity is zero by assumption,
while a “—“ indicates that a quantity is zero by definition. For example, by definition
loyal voters stick with their party, something impossible if they cast their plurality
vote for a candidate from a different cartel than their most preferred party.
4 Observing strategic voting in Italian elections
The dataset
Data consists of district-level election results from the 1996 Italian elections. The unit
of analysis is the single-member constituency, in 474 districts for each election.6
Partitioning the observed vote
A unique feature of electoral competition in Italy is thus the endorsement of SMD
candidates by electoral cartels of parties, in a situation in which the endorsed
candidate is affiliated to a party belonging to the cartel that also has its own PR list.
Consider the example of the first SMD in the first PR constituency from the 1996
election, shown in Table 2.
Each SMD candidate is sponsored by a “cartel” which consists of a bloc of parties or
possibly a single party. Political competition in 1996 was structured around two main
cartels which competed in every SMD.
1. L’Ulivo: consisting of Fed. Dei Verdi, Pop-SVP-PRI-UD-Prodi, PDS, Lista Dini,
and PS D’AZ. Although not formally part of the Ulivo cartel, Rif. Com. is also
included because of the nature of their exclusivity pacts in 1996 which functioned
like the formal cartel agreements (generally under the Progressisti ’96 label).
2. Polo: consisting of CCD-CDU, Forza Italia, and Alleanza Nationale.
A residual “group” contesting SMDs, which we can think of as an implicit cartel, is:
3. Other: consisting of all other multi- and single-party cartels.
6
Although there are 475 SMDs in the electoral system, one district (Val D’Aosta) is omitted here since
it has no corresponding PR district.
8
Each SMD candidate was also affiliated with some party or party bloc (such as POPSVP-PRI-UD-Prodi) that had established a list in the PR constituency containing the
single-member district in question.
SMD election
Cartel Name
Ulivo [Pu]
Polo [Pp]
(Other: Part Umanista)
(Other: Lega Nord)
(Other: Piemonte)
[Other Total Po= 11,910]
Cartel plurality vote
in SMD%
37,586
35,221
718
9,260
1,932
PR party affiliation of
cartel candidate
POP-SVPFORZA ITALIA
PART. UMANISTA
LEGA NORD
PART. FEDERAL
PR election
PR List
FED.DEIVERDI
LISTADINI
PDS
RIF.COM.
POP-SVP- [Lu]
[Ulivo Total Cu= 37,617]
ALLEANZA NAZ.
CCD-CDU
FORZAITALIA [Lp]
[Polo Total Cp=35,755]
LEGANORD
PART.FEDERAL.
PART.UMANISTA
[Total Lo= 7,764]
NUOVEENERGIE
PANNELLA-SGARBI
SOCIALISTA
VERDI-VERDI
[Other Total Co= 12,150]
Party PR list vote in
area of SMD%
2,233
5,968
14,240
9,828
5,348
Cartel membership of
PR list party
Ulivo
Ulivo
Ulivo
Ulivo
Ulivo
14,021
3,588
18,146
Polo
Polo
Polo
7,346
176
242
Other
Other
Other
88
2,923
265
1,110
Other
Other
Other
Other
Table 2: SMD and list-PR candidates and results in Italy: District 1, Constituency 1,
1996
This unique set of institutional rules and political practice makes it possible to
observe the following quantities in each SMD:
•
•
•
•
•
each candidate’s plurality vote;
each candidate’s cartel affiliation;
the PR-list party or party bloc officially endorsing each SMD candidate;
at the district level, the total PR list votes received by each cartel, obtained by
summing the votes of party lists known to be members of each cartel.
at the district level, the list vote for each PR-list party or party bloc.
9
From prior political knowledge we know which parties or party blocs are members in
each cartel, and we know that this is invariant across all districts, except for the northsouth differences in 1994.
Parameterization of Strategic Voting
Cartel List Vote
Cp = 35,755
Cu = 37,617
Co = 12,150
Voter Type
Loyalists
Strategic
Non-Strategic
Loyalists
Strategic
Non-Strategic
Loyalists
Strategic
Non-Strategic
Cartel Plurality Vote
Pu = 37,586
Po = 12,150
Pp = 35,221
Lp = 18,146
Rp
0
-0
Nup
-0
Nop
-0
Npu
Lu = 5,348
Ru
0
-0
Nou
-0
Npo
-0
Npo
Lo = 7,764
Ro
0
Table 3: Observed and Unobserved Parameters, District 1, Constituency 1.
Each of the nine computed quantities is aligned with the plurality candidate(s) from
which it derives. In the case of the other candidates the computed quantities is
arbitrarily placed next to the Lega Nord candidate.
Because each row and column in the composition in Table 3 contains the quantities L,
and since we assume that voters will always choose their party’s candidate if one
exists, we can simplify the compositional matrix by eliminating the Li’s. This yields
two new sets of quantities, more closely focused on our parameters of interest:
Tp = Cp - Lp
Tu = Cu - Lu
To = Co - Lo
Xp = Pp – Lp
Xu = Pu – Lu
Xo = Po – Lo
T’s are “frustrated” voters whose most preferred party (defined by their list vote) has
no candidate in the single-member district, and therefore have Transferred their vote
to another party in the SMD.
X’s are the “eXcess” votes received by a plurality candidate over his or her loyal core
of voters who cast a list ballot for that candidate’s party.
Since the vote total V now reflects the subtraction of Lp, Lu, and Lo, we denote VT as
the total transferred votes, where VT=V - L. We use this designation to reflect the
adjustment of the “excess” votes for the difference between invalid votes in the two
ballot. We take this adjustment from the transfer votes for the Other category To since
10
this category is not of direct interest and likely to be least affected by the loss of
information.7
This reduces the voting question to the following 3 x 3 table for each district, shown
as Table 4. For illustrative purposes we have also filled in the marginals with actual
votes from Constituency 1, District 1 from the 1996 election.
Xp
Rp
Nup
Nop
17,075
Tp
Tu
To
Xu
Npu
Ru
Nou
32,238
Xo
Npo
Nuo
Ro
4,146
17,609
22,441
13,409
53,459
Table 4: Vote Transfers in a District, 3x3
The empirical question in which we are interested then becomes one of estimating the
balance of strategic versus non-strategic voting. When voters were faced with a
contest in single-member districts where their most preferred party had no candidate
(frustrated or Transfer voters), then which cartel candidates picked up the eXtra
votes? By estimating the quantities Ri and Eij we obtain answers to these questions
and estimates of the extent of strategic voting for each cartel, at the district level.
The problem expressed in the 3x3 Table 4 is one of ecological inference, since it
characterizes individual-level voting behavior where only aggregate vote quantities
are observed. To estimate the cells at the district level, we use a two-stage application
of King’s (1997) EI algorithm. Because this method does not work with 3x3 tables,
we need an additional assumption.
Simplifying Assumption: Voters preferring a party who is not in either the Polo or
Ulivo cartels will always be considered non-strategic, such that Ro=0 and Noo=0. This is
plausible since only the Polo or Ulivo have a chance of winning the election overall, and
such voters thus do not have a strategic option that allows them to transfer within a cartel
that might win the election. This implies that Nop, Nou, and Noo be assigned their
expected values (rc)/n, or (TiXj)/VT.
Tp
Tu
Xp
Rp
Eup
12,792
Xu
Epu
Ru
24,152
Xo
Epo
Euo
3,106
17,609
22,441
40,050
Table 5: Constituency 1, District 1 Example as a 2x3 Table
The third row of the adjusted Table 4 using the Constituency 1, District 1 example
then becomes {4283, 8086, 1040}. Subtracting this from the X marginals yields the
7
For instance, in the 1996 example of constituency 1, district 1 there were 4,667 invalid plurality
ballots, but only 3,862 invalid list ballots. To make P=C we added P - C to To, in this case negative
805 votes. [KB: provide some stats here on general patterns of adjustments.]
11
2x3 Table 5, whose cells can be estimated using King’s (1997) EI algorithm. The
quantities to be estimated using King’s EI parameterization are then:
Xp
b
Tp
λ
Tu
λwi
i
Xu
1-λ
Xo
b
i
1 - λwi
b
i
1 - βbi
Xi
βwi
1 - βwi
1 - Xi
β
Table 6: King’s 2x3 EI parameters to be estimated
The four parameters can be estimated by using King’s EI software8 and the two step
ei() and ei2() procedures for the nested tables. The corresponding estimates will be
equivalent to:
Rp*
=
E(λbi)
Ru*
=
E(1 - λwi)
Eup* =
E(λwi)
Epu* =
E(1 - λbi)
Epo
=
E(1 - βbi)
Euo
=
E(1 - βwi)
Proportion of frustrated Polo voters not voting for a candidate
from the Other cartel, who stayed with a Polo candidate
Proportion of frustrated Ulivo voters not voting for a candidate
from the Other cartel, who stayed with a Polo candidate
Proportion of frustrated Ulivo voters not voting for a candidate
from the Other cartel, who voted for a Polo candidate
Proportion of frustrated Polo voters not voting for a candidate
from the Other cartel, who voted for a Ulivo candidate
Proportion of frustrated Polo voters voting for a candidate from
the Other cartel
Proportion of frustrated Ulivo voters voting for a candidate from
the Other cartel
The starred (*) quantities differ from the originals from Table 5 in that they are for
just the subset of the frustrated voters that do not vote for a candidate from the Other
cartel. This is primarily a by product of the EI parameterization of King’s model, but
also has an intuitive interpretation. The focus of the Epo and Euo estimated directly by
the βs draws attention to the non-rational voters that decided not to vote for either
main coalition. The starred quantities estimated by the λs, on the other hand, draw
attention to the voters who, having decided to vote for one of the main cartels, have
either voted rationally or non-rationally by switching to the rival cartel. The
interpretation is applied practically in the next section.
Results
Results from the estimations appear in Table 7. The principal results can be simply
stated. Of the frustrated Polo voters, 4.2 percent (Epo) cast their votes non-strategically
for a candidate from the Other cartel. This compares to 8.1 percent (Euo) for the
frustrated Ulivo voters. Of the frustrated voters who did not vote for a candidate in
the Other cartel, 74.8 percent (Rp) of the Polo voters on average voted strategically
for a candidate from the Polo cartel, as opposed to 91.1 percent (Ru) of the Ulivo
voters on average voting strategically for a candidate from the Ulivo cartel.
8
Or Benoit and King’s EzI software. See http://Gking.Harvard.Edu/software.shtml
12
EI/EI2 Estimation results
(aggregate quantities of interest)
Parameter
Estimate
βb
Model Quantities of Interest
(aggregate point estimates)
(standard error)
.9578
(.02911)
Rp*
.7479
Ru*
.9119
βw
.9187
(.02465)
N
412
Eup*
.0881
Esims
Log-likelihood
1,000
1166.9868
λb
Epu*
Euo
Epo
.2521
.0813
.0422
.7479
(.01227)
. 0881
(.01099)
412
1,000
952.79629
λw
N
Esims
Log-likelihood
Table 7: Aggregate Ecological Inference Estimates, 1996 Data
This suggests that Ulivo voters were as a whole much more “strategic” in the sense
we have identified here in that they did not split their votes between two main cartels
nearly as much as Polo supporters.
Figure 1 illustrates graphically the difference in strategic behavior between frustrated
Polo and Ulivo voters. At the district level, Ulivo voters were rational in higher
proportions than Polo voters, as evidenced by the large number of points below the
diagonal (which is unfortunately not shown in this graph). Figure 2 shows in addition
that among the frustrated Ulivo voters that did not vote rationally, many more chose a
candidate from the Other cartel rather than vote for a candidate from the Polo cartel.
In the next section we attempt to explain the variation in these levels of rational and
non-rational voting by mapping them to various systematic factors at the district level.
13
1
Rational Polo Voter Proportion
.8
.6
.4
.2
0
0
.2
.4
.6
Rational Ulivo Voter Proportion
.8
1
Figure 1. Scatterplot of Point Estimates of Ru by Rp at the District Level
.5
.45
Frustrated Polo Voting for Other
.4
.35
.3
.25
.2
.15
.1
.05
0
0
.05
.1
.15
.2
.25
.3
.35
Frustrated Ulivo Voting for Other
.4
.45
.5
Figure 2. Scatterplot of Point Estimates of Euo by Epo at the District Level
14
5 Systematic Determinants of Rational Voting
In this section we begin to analyze the variation in our estimated district-level
strategic voting for each cartel. This section remains preliminary but we start by
examining the notion that strategic voting should be most prominent in districts where
inter-cartel competition is the most intense. This means that the level of strategic
voting should be negatively related to the size of the gap between the votes of the two
main cartels—in other words |Cp-Cu|. If the size of this gap is very small, then the
incentives for strategic voting are much higher, since such voting is more likely to
influence the final result. If the size of the gap is very large, then voters may perceive
that there is no particular benefit in strategic voting. In effect, therefore, we uses ur
estimated levels of strategic voting in each constituency to test in a more
comprehensive way the proposition, tested by Cox (1997: 82-83) for Germany, that
the closeness of the plurality election result encourages strategic voting. We test this
hypothesis in Table 8, which shows very clearly that there is indeed a statistically
significant negative relationship between the closeness of inter-coalition competition
in a district and the level of strategic voting for both electoral cartels.
Dependent Variable
Independent
Variable
Constant
|Cp-Cu|/ΣC
|Pp-Pu|/ΣP
|Lp-Lu|/ΣC
SEE
R2
N
Ru
Rp
Euo
Epo
.8098
.6887
.1111
.0483
(.0074)
(.0110)
(.0074)
(.0015)
-.5145
-.5466
.4785
.0338
(.1786)
(.1566)
(.2002)
(.0225)
.5431
.8120
-.5147
-.0598
(.1691)
(.1569)
(.1875)
(.0230)
.2667
.0031
-.2703
-.0310
(.0621)
(.0739)
(.0682)
(.0010)
.090
.18
412
.127
.13
412
.094
.16
412
.017
.07
412
Table 8. Regressions of Estimated District-Level Quantities on Inter-Coalition
Competitiveness. OLS regression with heteroskedasticity-consistent standard errors.
Bold coefficients are statistically significant at the p>.01 level.
More things to investigate:
•
Intra-coalition conflict. Another thing that we test is the theory of Tsebelis that
greater intracoalition competition is likely to lead to more rational voting[ET5]. As a
measure of inter-coalition competition, we consider the following measure of Neff/N,
where Neff refers to the “effective” number of parties in a cartel in a particular list
district, and N is the total number of parties in the cartel. This figure, defined for each
cartel, produces a ratio of competitiveness. The closer the ratio is to 1.0, the more
competitive the district, since the numerator will be closest to the denominator as the
votes between parties become more equal.
15
•
Policy or spatial considerations. The idea here is that we should link rational and
expressive behavior to the spatial location of the party for each coalition sponsoring the
sole plurality candidate (for example, being an “extreme” candidate). It should be the
case that, the closer the sincerely preferred party to the center, the greater the incentive,
if this party is not the SMD candidate, to vote “rational-non-strategically” for a party of
another cartel – i.e. the lower the level of strategic voting (in our terms) we observe.
(The rational-non-strategic voter votes perhaps for the next-closest party, even if this is
out of the first-choice party‘s cartel – and even therefore if this vote will put a rival
cartel, not including the first-choice party, into office). This translates into the
prediction that our levels of strategic voting should be highest when one of the cartel’s
centrist parties is the SMD candidate – since this reduces the „rational-non-strategic“
incentives to defect from the cartel to a rival cartel. These incentives will be greater
when the cartel candidate is a more extreme candidate. In terms of the data below, this
implies that SMD candidates from RI for the Ulivio and CCD-CDU for the Polo
should generate the highest levels of strategic voting.
TABLE: Standardised economic left-right scores for parliamentary
documents and standardised scores on comparable expert surveys, Italy
1996.
Party
Computer
coding
5.1.1.A Ispo
survey
Abacus survey
economic L-R
5.1.1.A Econo
mic L-R
RC
PPI
Greens
PDS
CCD
CDU
RI
AN
FI
NL
Std score
Std scores
-1.88
-0.67
-0.54
-0.43
0.16
0.16
0.20
0.80
1.07
1.30
-1.84
-0.38
-1.29
-0.52
0.34
0.40
0.87
0.20
1.10
1.12
Std scores
-1.82
-0.32
-1.17
-0.67
0.45
0.50
0.65
-0.02
1.33
1.07
•
Regions. We can test differences between regions using dummy variables.
•
Presence or absence of certain parties. Mostly these would be parties present in the
Other category. Like: Lega Nord, Communists, etc.
16
6 Conclusions
References
Cox, Gary. 1997. Making Votes Count: Strategic Co-ordination in the World’s
Electoral Systems. Cambridge: Cambridge University Press.
D’Alimonte. Roberto. 1998. Appendix: The Italian elections of 1996. European
Journal of Political Research. 34: 171-174
Farquarson. 1969.
King, Gary. 1997. A Solution to the Ecological Inference Problem. Princeton:
Princeton University Press.
Laver, Michael. 1987. The logic of plurality voting in multiparty systems. In Manfred
Holler (ed) The Logic of Multiparty Systems. Dordrecht, Kluwer Academic
Publishers.
17
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