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Measuring Party Competition from Legislative Speeches:
Analyses of Japanese Parliamentary Debates, 1953-2011
Airo Hino†, Luigi Curini∗, and Atsushi Osaki†
Paper prepared for the 2013 ECPR General Conference, Bordeaux
Work in progress – do not quote without Authors’ permission
Abstract
Among the existing measures of legislative behaviour, such as the use of roll call votes,
this paper attempts to add to the list by proposing a new measure of party competition
by using legislative speeches. Legislative speeches have become increasingly accessible
through digitalised databases in the recent years and we demonstrate how the use of
legislative speeches can contribute to our understanding of inter-party and intra-party
competition in the legislative arena. The use of legislative speeches to estimate positions
of political actors is indeed an important venue not only because of its recent
development in the scaling technique but also because of the limited availability of roll
call data in Japan. Our validations with external events and consequences seem to
suggest that the dimension extracted from Wordfish reflects a line of conflict between
government and opposition rather than an ideological left-right dimension.
† Waseda University. Email: [email protected]. ∗ University of Milan. Email: [email protected] † Waseda University. Email: [email protected].
2
Introduction
In this paper, we propose a new measure of party competition which captures
party-dynamics based on the analysis of legislative speeches. Legislative speeches have
indeed become increasingly accessible through digitalised databases in the recent years
and the methods to analyse them, especially in an automated way, have increased
notably in the literature (Grimmer and Brandon 2013). The well-known method
advanced by Proksch and Slapin (2009), known as Wordfish, allows in particular to
extract the positions of actors along an underlying latent dimension. The substantial
content of such dimension, however, remains to be properly understood, contrary to
other methods, as we will discuss below. In this sense, by codifying speeches made by
prime ministers and party representatives in the parliamentary sessions of the Japanese
Diet from 1953 to 2011, we show how the recovered positions can be better understood
as reflecting the intensity of government and opposition confrontation and its
development over time, rather than a mere ideological scale. We then illustrate how
such government-opposition divide is conditioned by electoral cycles. Our analyses
show that parties oppose to each other more intensely prior to elections but to a lesser
extent in the middle of electoral cycles. The new measure also appears to account for
other dimensions of legislative politics such as the survival rate of Japanese
governments and the duration of time needed for governments to pass their proposed
bills. While this measure could also be applied to the studies of coalition politics and of
intra-party politics of factions, we hope to show in this paper some examples for an
illustration of the measure and illuminate a possible venue in the future research on
legislative politics. Below we will first review the literature that measures party
competition and discusses our strategies in coding parliamentary speeches.
3
Measuring party competition in political science
A variety of scaling methods are available to date in political science to measure
positions of political actors, yet most of them are confined to the positions of political
parties at the time of election. The rich list of these measures ranges from the coding of
party manifestos (Budge et al., 2001; Klingemann et al, 2006), expert surveys (Benoit
and Laver, 2006; Hooghe et al., 2010), and to voters’ evaluation in surveys (e.g.
Comparative Study of Electoral Systems series). Similarities and differences of each
approach can be summarised with a triangular form in Figure 1.
Figure 1. Estimating party positions
Party Manifestos
Election Data
Party Positions
Voters Evaluation Expert Surveys
The coding of party manifestos and the evaluation of party positions by voters in
surveys are similar in that political parties and voters both perform as actual actors in
the electoral processes. At the time of election, political parties propose their electoral
pledges and voters evaluate the stances of each party. Expert surveys do not fit in this
group as experts are not direct political actors in the electoral processes. Instead, expert
4
surveys and voters’ evaluation do share the feature of evaluation of parties’ positions as
both approaches evaluate party positions in a pre-determined survey. The coding of
party manifestos is different from this group of survey-based evaluation approaches
since it is based on the coding of actual political texts instead. Lastly, the coding of
manifestos and expert surveys have things in common with regard to the contexts of
data collection. As both data are collected in the uniform manner for every election, it is
relatively easier to compile a cross-national and time-series dataset. Recent efforts in
coordinating comparative and national election surveys could produce such
cross-sectional and time-series dataset but it is generally more costly and difficult to run
randomly sampled surveys for every election. In this regard, the coding of manifestos
and expert surveys could produce a dataset in a standardised form across different
countries over time with less difficulty than voters’ surveys.
All three approaches seem to be first limited with a range of cross-temporal dimension
and second confined to electoral settings. This is quite natural as all three approaches
are based on elections which take place in the 2-5 years cycles. But this does not mean
that positions of political actors do not change between the t-1 and t elections. We do
know from daily observations of particular parties that parties do change their positions
between cabinets and in relation to a particular legislation as well as in reaction to the
changes in society and the world affairs (Laver and Benoit 2003, Curini 2011).
Moreover, the same number of parties can be modified in the between-election periods
due to splits and mergers (Laver and Shepsle 1998). Similarly, the ways in which
coalition politics takes place in the legislature could also change in reaction to the above
conditions.
5
Secondly, the three approaches could also suffer from their limitations in applying to
other institutional settings such as a legislature and a government than electoral settings.
At the election time, parties mainly speak to voters. At the normal (i.e. non-election)
time, legislators mainly speak to themselves and to a lesser extent speak to voters. The
institutional incentives are clearly different when politicians are trying to garner votes at
an election and legislators are trying (not) to pass proposed bills or (not) to support the
government. Given that political parties shift their vote-seeking, policy-seeking, and
office-seeking incentives according to the institutional settings (Strom, 1990), one needs
to be careful in using the party positions derived only from the electoral settings. In the
normal time, parties’ behaviour could reasonably be principled by a government and
opposition divide. If this is the case, one would need to measure the degree of party
competition with a different scale that would reflect a divide in the parliamentary arena.
In this perspective, records available in a legislature are precious sources for extracting
a dimension that would capture the natural relationships among parties in the
parliamentary arena. The roll-call votes in a legislature have been analysed extensively
to estimate the stances of political parties, factions, and each individual legislator
(Clinton et al., 2004; Poole 2005; Hix et al. 2005; Curini and Zucchini 2010). There
have been continued discussions as to the nature of such extracted dimensions derived
from the roll-call scaling. At least when we focus on parliamentary democracies rather
than on presidential systems (on this point, see Laver 2006) what is measured from
roll-calls is indeed the structure of the “revealed behavioral space” (Hix and Jun 2009)
instead of the underlying ideological dimension. As a consequence, normally by
6
applying roll-call analysis to parliamentary democracies what a researcher gets is the
positions of MPs along a government-opposition divide (Curini and Zucchini 2012).
The measures produced by a roll-call analysis, however, exactly as the previous
methods, tend to remain relatively static: usually what we get is the positions of MPs
over one entire legislature. Albeit of course a roll-call analysis can be applied to a
specific sub-period during a legislature (Poole 2005), the need to have enough
observations (i.e., a relatively large number of roll-calls to which applying the analysis)
indirectly limits such possibility.
Moreover, a roll-call analysis cannot be applied in all those contexts in which roll-call
vote data are not available or are available only in a limited range, as it happens in the
Japanese case.1 The roll-call data are of limited use in Japan since most of the proposed
bills pass in both Houses of the Japanese Diet without an actual voting of each legislator
(but with a majority of legislators standing in the floor). One must thus bear in mind that
even with the roll-call vote data, which is available in the case of the Japanese
legislature only in a limited range, an extracted dimension needs to be carefully
validated if it were to be used in empirical analyses. Yet, for the purpose of measuring
the degree of party competition in Japan, one would need to look for other sources.
For the above reasons, this paper explores a scaling of party competition in the Japanese
Diet from legislative speeches. Legislative speeches are digitalised in recent years and
1 Only when the President of each House requests a formal voting or one-fifth of the legislators request a formal voting, a formal procedure of voting takes place according to Article 151 and 152 of the Rules of the House of Representatives and Article 138 and 139 of the Rules of the House of Councillors.
7
all the Diet record in Japan can be publicly accessed through the Internet2. If we can
somehow extract a dimension of party competition from parliamentary debates, changes
and variations of party positions can be measured in a richer cross-temporal dimension
at least in a yearly fashion as parliamentary sessions can be observed every year.
Scaling party positions from legislative speeches would be classified as the same
approach with the coding of manifestos seen in Figure 1 as positions are derived from
observing messages of actual political actors. We will thus briefly review some scaling
techniques below applied to the coding of party manifestos for our purposes.
Scaling legislative speeches in the Japanese Diet
The content analysis of political texts has developed through the stream of manual
approaches of human-coding and the stream of automated approaches of
computer-coding. The examples of human-based coding in measuring party competition
are exemplified in the coding projects of party manifestos. The Comparative Manifestos
Project (CMP) (Budge et al., 2001; Klingemann et al., 2006) requires trained coders to
classify quasi-sentences of manifesto texts into pre-determined policy domains. Another
manifesto project as demonstrated in Party Change Project (PCP) (Harmel et al., 1995)
asks coders to judge policy positions from the entire manifestos. In a similar vein,
projects in Japan classify electoral pledges publicly distributed during the election
campaign into administrative domains (Shinada, 2006; Kobayashi, 1997).
2 The National Diet Library makes the Diet record available through the following URL
(http://kokkai.ndl.go.jp/).
8
The stream of computer-assisted approaches ranges from a supervised method of
identifying words for human-coded quasi-sentences in the CMP data (Pennings and
Keman, 2002), of calculating Wordscores from training texts (Laver et al., 2003), and to
an unsupervised method of Wordfish which locates words on one dimension based on a
Poisson item response theory (Proksch and Slapin, 2008). The number of application of
these computer-assisted approaches has accelerated in the recent years. Among these
applications, an important contribution in the context of the Japanese politics has been
made by Proksch, Slapin, and Thies (2011) which applied Wordfish to the Japanese
party policies in news article (taken as surrogates for party manifestos) and extracted an
ideological left-right dimension in the Japanese political spectrum in the post-war years.
Although there are advantages and disadvantages of both human-coded scaling and
computer-assisted scaling, this paper pursues the latter approach of an automated text
analysis. The obvious issue would be a trade-off between validity and reliability in
adopting the human-based coding and computer-based coding (Krippendorff, 2004;
Riffe et al., 2005). The computer-assisted scaling has the virtue of holding high
reliability as the analyses can be replicated and same conclusions can be retained as far
as the procedures and data sources are made public. The computer-based coding might
thus have an edge against the manual human-based coding which would have to
repeatedly run inter-coder reliability test (e.g. Hayes and Krippendorff, 2007). Yet, the
downside of the automated scaling is a potential lack of validity in the scaled content
and one needs to check if the measurement really taps what is supposed to
operationalize. In this regard, the human-based coding naturally has the advantage.
9
To scale a dimension of party competition, we apply an unsupervised computer-
assisted scaling. The reason for applying an unsupervised method derives from our
approach to keep all options open and not to predetermine the nature of party
competition in the parliamentary arena. As an unsupervised computer-assisted scaling,
we apply the Wordfish technique of Proksch and Slapin (2008) to extract a dimension
of party competition from the Japanese legislative speeches. Like the Proksch, Slapin,
and Thies (2011) which applied the Wordfish to the Japanese party pledges, we repeat
the similar exercise with the legislative speeches in the Japanese Diet. While Proksch,
Slapin, and Thies (2011) found that the extracted dimension indeed captures the
ideological left-right dimension, we are not necessarily confined to the hypothesis of
ideological party competition in the parliamentary arena. Since the political text in our
analyses stem from a different institutional setting, the Japanese legislature, as opposed
to the electoral settings in most of the previous studies of political texts, we expect that
an extracted dimension could reasonably be different from an ideological dimension.
While keeping our reading of the scale unfixed, we tentatively hypothesize that the
dimension of party competition extracted from an unsupervised computer-assisted
scaling is concerned of a conflict between government parties and opposition parties. As
the language spoken on the floor is primarily directed to other delegates, or cabinets and
opposition parties rather than to voters, one could naturally expect that the dimension of
conflict may well be different from the ideological one found with different political
texts. On top of vote-seeking incentives, political parties have office-seeking incentives
as well as policy-seeking incentives (Strom, 1990). If that is the case, the line of conflict
may not be exclusively conditioned by an ideological dimension driven by
10
policy-seeking incentives but also be determined by a power-oriented dimension driven
by office-seeking incentives. This could be more likely to be the case in parliamentary
democracies where exchanges among parties tend to be driven by power-seeking games
in an arena type parliament rather than policy-seeking coordination in a transformative
legislature (Polsby, 1975). This provisional hypothesis is also in line with the existing
literature on the Japanese parliament which has suggested that it has high viscosity
attributed to opposition parties’ strategies (Mochizuki, 1982). Opposition parties try to
influence legislative processes by employing non-policy tactics, i.e. sabotaging sessions
and negotiating the parliamentary schedules, not necessarily by policy perspectives.
Given that the computer-assisted scaling requires some validations of the scaled content,
this paper attempts to do so by examining how it appears to be associated with
contextual variables in the Japanese parliamentary arena. By correlating the scale
obtained from the legislative speeches with external variables such as electoral cycles,
the percentage of succeeded bills, and the survival rate of government, we will check for
the “predictive validity” of the scale (Grimmer and Stewart, 2013: 21). This is one of
the recommended strategies for validating an unsupervised scale. Of course, one could
also compare different scaling approaches for validation for “semantic validity” and
“convergent validity” as outlined by Grimmer and Stewart (2013). Although this would
certainly be another possibility, this paper pursues cross-examinations with important
contextual variables often used in empirical analyses of legislative and election studies
to test for the “predictive validity” and external validity of the scale.
Extracting a dimension by Wordfish
11
We have selected all the speeches in the House of Representatives following the Prime
Minister’s general policy speeches and the questions from each party representative.
Where there are more than two speeches from the same party in the same session, we
have selected the speaker that is of higher rank in the party. Overall 429 speeches over
79 sessions, and almost 19,000 words/kanjis are collected from 1953 (Diet 18) to 2011
(Diet 179) from the database of the National Diet Library.
Coding procedures take the following two steps. First, we split the speeches into words
through tokenizer engines such as ChaSen and/or MeCab. The difficulty of
computer-assisted text analysis in Japanese is that a Japanese sentence is only
distinguished by commas, and words are put in sequence without spaces in between. We
thus applied the two main tokenizer engines developed in the past twenty years (and the
results remain largely identical). This procedure produces a data matrix in which the
frequencies of the words that appeared in the speech of each parties are recorded (i.e. all
the words that appeared in the speech listed in the rows and the parties in the columns).
Second, after having transformed from words to numbers, we estimate the positions of
each speaker (i.e. party position) through the automated scaling model of Wordfish
developed to run with the statistical software R (Proksch and Slapin 2008). The
Wordfish analyses textual documents with Poisson item response theory, comparing the
frequencies of words contained in each text, under the assumption that, for each
document, the words’ relative frequencies are informative of the general position of that
text. Through this, the Wordfish arrays documents along a single latent dimension,
providing estimates of their positions on the scale. The model is expressed as follows:
12
, where:
yij is the count of word j in actor i‘s document (in our case legislative speeches)
α (alpha) is a set of actor (i.e. speaker) fixed effects
ψ (gamma) is a set of word fixed effects
β (beta) is an estimate of a word specific weight capturing the importance of word j in
discriminating between positions
ω (omega) is an estimate of actor i's position.
The main advantage of Wordfish is its ability to track variations in actors’ preferences
across time by estimating the position of actor i at time t, regardless of its position at
time t-1. Indeed, any shift in the position of actor i is only due to a change in the set of
words used by that actor that expresses an actual modification of its
position/preferences, not an artefact of the model. Owing to this feature, Wordfish
makes it possible to produce valid time-series estimates. This statement holds, however,
only if the word usage and the political language remain relatively constant over time
(Proksch and Slapin, 2009). Given the wide cross-temporal range of our analyses, we
want to make sure that our results are not biased by changes in the actual meaning of
some political words. For this reason we split our data in two separate time periods,
choosing 1989 as the dividing line, assuming that political language changed after the
collapse of communism and the rise of new technology and globalised economy (see
Ceron 2012 for a similar choice).
13
Figure 1 shows a scatterplot of each word in the two dimensions of beta (on the
horizontal axis) and gamma (on the vertical axis) for the speeches before 1989 and
Figure 2 is a scatterplot of each word for the speeches after 1989. Both figures show
that some words are located on the two extremes on the horizontal axis, scoring high
positive or negative beta coefficients. This suggests that these words are powerful
discriminators of party positions. At the same time, these words tend to have low
gamma coefficient on the vertical axis, meaning that they appear rarely in the speeches.
Those words used often in the speeches tend to have high gamma coefficients but hardly
distinguish party positions (i.e. low beta coefficients). In general, most words are
located in the triangle of the high gamma / low beta corner, the low gamma / high
positive beta corner, and the low gamma / high negative beta corner.
14
Figure 2. Word estimates by Wordfish for the speeches before 1989
Figure 3. Word estimates by Wordfish for the speeches after 1989
15
Our choice to split the data before and after 1989 appears to be reasonable. Both figures
display some typical words related to the underlying dimension of beta coefficients.
Figure 2 and Figure 3 show some selected words used in the respective period.
Noticeably, recent words appear in Figure 3 such as “genome”, “interactive”, and
“working poor”. Likewise, relatively old-fashioned words such as “poor peoples” and
“mystery” appear in the speeches before 1989. Analysing the speeches all together
would have simply produced a dimension that captures the newness and oldness of the
words spoken in the speeches across the decades.
The semantic validity of the words appears to be mixed. On one hand, ideological
left-right terminologies seem to match with the dimension (“tradition” with a highly
positive beta coefficient and “poor people” with a highly negative beta coefficient in
Figure 1). On the other hand, government-opposition terminologies seem to be relevant
(“submitting bills” and “passed bills” with highly positive beta coefficients and “double
swords” with a highly negative beta coefficient). Further analyses are required to
cross-examine the semantic validity of the scales. Yet, the purpose of this paper is to
validate the scales with the contexts of the Japanese politics and to associate with other
contextual variables. We will turn below for the tests of “predictive validity” with
external events and political consequences at different levels of political processes.
Validating the Wordfish scale with political events
We will examine the validity of the extracted scale from Wordfish in two steps in the
following two sections. First, we will examine the changes of party positions in the
16
time-series from the 1950s to the present and cross-validate the scale with the political
events. Second, we will examine the Wordfish scale with other contextual variables. The
contextual variables consist of three levels of political processes: (i) electoral, (ii)
legislative, and (iii) executive. The details of these levels will be discussed in the next
section.
Before presenting the time-series changes of party positions, Figure 4 shows the overall
average of party positions throughout the decades. It appears that the parties are located
on the left-right ideological dimension in line with the conventional wisdom. Liberal
Democratic Party (LDP), the long-time ruling party of Japan, is located further to the
right; Japan Socialist Party (JSP), the major opposition party until the early 1990s, is
located on the left. The fact that Japanese Communist Party (JCP) is located further to
the left and that Japan Democratic Party (JDP), the major opposition party since 1998
and the governmental party between 2009 and 2012 is located on the moderate left seem
to further validate this axis as the standard left-right ideological dimension.
17
Figure 4. Average party positions on the wordfish scale, 1953-2011
However, the above reading of the dimension no longer holds once the estimated
positions are traced in the time-series. Figure 5 illustrates the shift of party positions
through the decades. As found in Figure 4, the overall trend is that LDP is located on the
upper side of the dimension (i.e. positive omega coefficient) and JSP and JDP are
located on the lower side (i.e. negative omega coefficients). The picture looks
remarkably different, though, when we look at the periods in which LDP went into
opposition. The first time when LDP went into opposition was in 1993 when eight
parties/groups including JSP formed the non-LDP coalition. JSP’s position jumps up to
the positive considerably and LDP’s position goes down to the negative for the first
time in the post-war period. The second time was in 2009 when LDP once again was
forced to be in opposition with the landslide victory of DPJ (JDP or DP in the figure).
18
DPJ goes up to the positive from the negative and LDP goes down to the negative from
the positive, virtually swapping their positions.
Figure 5. Changes of party positions on the Wordfish scale, 1953-2011
The time-series shifts of party positions seem to suggest that the extracted dimension is
the divide between government and opposition. It is quite unlikely to suppose that LDP
changed its ideological position from right to left in 1993 and 2009. Government parties
generally appear to be positive, while opposition parties mark negative coefficients. It
would be more reasonable to understand that the Wordfish score depicts a conflict
between government and opposition in the parliamentary debates.
19
It is important to note here that this divide of government and opposition is not an
artefact of Wordfish, nor the product of a uniqueness Japanese language. Proksch et al
(2011) has indeed demonstrated the ideological dimension applying the same scaling
method with manifesto documents. The only difference is the texts used for analyses.
While their analyses were based on electoral pledges of political parties, our analyses
were based on the words spoken in the parliamentary arena3. These differences seem to
suggest that institutional constraints clearly matter for the content of the scale.
Validating the Wordfish scale with political consequences
Based on the above finding, we will further validate the extracted scale with the
political trend variables. As described above, the trend variables consist of three levels
of political processes: (i) electoral, (ii) legislative, and (iii) executive. First, the electoral
level is concerned with the electoral cycles. We would expect that a conflict between
government and opposition intensifies when elections approach. Second, the legislative
level is concerned with the success rate of proposed bills. When a conflict between
government parties and opposition parties soars, we would expect that the success rate
would be diminished. Lastly, the executive level is concerned with the cabinet survival
rate. We would expect that when the conflict between government parties and
opposition parties is harsh, chances for cabinets to be terminated would be higher.
To put each of the three levels of analyses into the form of hypotheses, they should be
stated as follows.
3 The critique by Laver (2002) on using roll-call analysis in the context of a parliamentary (rather than in a presidential) democracy also applies to our case.
20
Hypothesis 1 (electoral cycles hypothesis)
When elections are closer in the electoral cycles, conflicts between government and
opposition intensify.
Hypothesis 2 (proposed bills hypothesis)
When conflicts between government and opposition intensify, chances are smaller for
cabinets to pass proposed bills.
Hypothesis 3 (cabinet survival hypothesis)
When conflicts between government and opposition intensify, chances are higher for
cabinets to be terminated.
To test these hypotheses, we need to operationalize the degree of Intensity of
Government and Opposition (IGO) divide. We could estimate such a measure over each
session k by adopting the Dalton’s index (2004) of party system polarization as follows:
, where VSjk is the seat share of party j during session k, Pjk is the position of party j
during session k over the latent government opposition scale, and is the average
position of parties along the same scale during session k.
Figure 6 shows the changes of the degree of IGO over the decades. The solid line
illustrates the weighted polarization (i.e. Dalton’s) index with interpolation and the
21
dotted line illustrates the index without interpolation. Clearly the IGO index is not
stable and it shows a relevant volatility in the short-term and across decades.
Figure 6. Changes of Intensity of Government and Opposition (IGO), 1953-2011
Hypothesis 1: Electoral Cycles Hypothesis
The IGO index is put as the dependent variable and the following possible determinants
of IGO are included in the model as independent variables. For the time variables, point
of the electoral cycle (both at the Lower and at the Upper house) and six dummies for
each decade starting since 1955 (omitted category: the decade between 1965-75) are
included. For the cabinet variables, majority margin of a cabinet, change in cabinet
composition between t and t-1 (a dummy), and length of the cabinet formula (i.e.,
number of sessions over which a given cabinet composition repeats itself) are included.
22
Table 1 shows the results. All the decades following the period of 1965-74 presents a
significantly lower value of IGO (but the decade 1995-2004). When a new government
formula is established, the confrontational attitude in the Parliament appears to decrease.
And most importantly, the variables concerning electoral cycles are found significant in
both the Lower House electoral cycles and the Upper House electoral cycles.
Table 1. Determinants of the IGO index
23
Figure 7. Electoral Cycles of the Lower House and the IGO index, 1953-2011
Figure 8. Electoral Cycles of the Upper House and the IGO index, 1953-2011
In both situations, the salience of the government and opposition divide decreases until
the half of the respective electoral cycles and the intensity index starts to increase as the
subsequent election approaches. These results suggest that parties become
confrontational as they face elections ahead, for the sake of appealing to voters that they
are fighting against their opponents and making themselves stand out in election.
24
Hypothesis 2: Proposed Bills Hypothesis
We analyze here a measure of the legislative outcome, which is operationalized as the
ratio of cabinet-bills successfully converted in law (period: 1953-2001). We expect a
negative relationship between IGO and this ratio (the larger the intensity of the
confrontation between the cabinet and the opposition, the more difficult for the cabinet
to convert into laws its proposed bills). Control variables are the set of dummies for
decades, majority cabinet margin, the existence of a different majority between the
Lower and the Upper House, and the total number of cabinet-bills proposed during each
session.
Table 2. The IGO Index and the Rate of Successful Cabinet Bills
25
The results are shown in Table 2. The IGO Index indeed show a negative sign and
significant at 95% level. The majority different at the Upper House (so-called ‘twisted
Parliament’ in the context of Japanese politics) also has a negative effect as well as the
decade dummy of 1995-2001. Even after controlling for these variables together with
the number of cabinet submitted bills, the IGO Index appears to be significant. The fact
that the IGO Index is related to the actual legislative outcome further validates the scale.
Hypothesis 3: Cabinet Survival Hypothesis
We now apply the IGO Index to explain the outcome at executive level. As the
hypothesis suggests, the higher the intensity between government and opposition is, the
more difficult it should be for a government to survive. We run Cox Proportional
Hazards Model to estimate the effects of the IGO Index. In this case we expect a
positive impact of IGO on the hazard rate of the survival of Japanese Cabinets, i.e., as
IGO increases, the predicted chances of cabinet termination also increases (period:
1953-2011). The effect is estimated together with the control variables: majority cabinet
margin, the number of component of the cabinets, the existence of a different majority
in the Upper House, and the electoral cycles.
The results are presented in Table 3. There are two scenarios. First, whenever a cabinet
lasts more than one session, for all of our independent variables, we consider just the
first value that each of independent variables displays in the first session of the cabinet.
Second, whenever a cabinet lasts more than one session, for all of our independent
variables we consider their average values across the sessions along which the cabinet
survives. The results are intriguing as the independent variables indeed show an
26
expected sign with significance. The margin of cabinet and the number of components
in cabinet both show positive signs, suggesting that the cabinet increases chances of
being terminated as the margin of cabinet is bigger and the number of parties in
coalition government increases. The electoral cycle variables are as expected negative
for the Lower House and positive for the Upper House elections. The ‘majority different
in the Upper House’ variable also has a positive sign as expected. These results are all
significant and are robust for both scenarios. And most importantly, the IGO Index has a
significantly positive effect on the chances of government termination. The fact that the
IGO Index is significantly related to the duration of cabinets even after controlling for
other relevant variables validates the extracted scale also at executive level.
Table 3. The IGO Index and the duration of Japanese cabinets, 1953-2011
27
Further validations with the manifesto scaling
Given that the Wordfish score was significantly related at all three levels of political
process, the electoral, the legislative, and the executive, one may argue that the
“predictive validity” is high enough to suggest that the extracted dimension is indeed
the index of government and opposition divide. Yet, we are still not sure if the extracted
dimension is really different from the findings in the previous studies which validated
the ideological left-right profile of the Wordfish score based on electoral pledges
(Proksch, Slapin, and Thies, 2011). To further validate the IGO Index, our final
analyses try to test the ideological scale and the IGO Index simultaneously.
First, we have tested the correlation between the left-right index from the CMP dataset
and the IGO Index. The result was a low correlation (.33) between the two indices. This
already testifies to the fact that these two indices measure to a large extent two different
phenomena. Second, we have estimated the same models of the proposed bills
hypothesis and of the cabinet survival hypothesis together with the CMP index.
Table 4 and Table 5 report that the IGO Index works even after controlling for the CMP
index, while the CMP index is never significant in both analyses. This once again
confirms that the IGO Index and the CMP Index are relatively independent of each
other and that the ideological left-right index derived from manifestos documents does
not have “predictive validity” of the political consequences at legislative and executive
levels examined in this paper.
28
Table 4. The IGO Index and the Rate of Successful Cabinet Bills (with CMP Index)
Table 5. The IGO Index and the duration of Japanese cabinets, 1953-2011 (with
CMP Index)
Conclusion
This paper attempted to scale party positions from legislative speeches in Japan. This
attempt had advantages: first to enrich cross-temporal variations of party positions, and
second to extract a dimension relevant to the parliamentary setting. We have tried to
validate the dimension extracted from the unsupervised scaling by Wordfish in relation
29
to the political events and consequences in Japan. The empirical analyses at electoral,
legislative, and executive level all appeared to support the idea that the Wordfish score
reflects a divide between government parties and opposition parties. We measured the
extent to which parties oppose to each other by the Index of Intensity of Government
and Opposition (the Index of IGO) for testing the respective hypotheses of electoral
cycles, proposed bills, and cabinet survival. The Index of IGO appeared to be
significantly related to all three levels of political process and this effect was robust
even after controlling for the ideological index derived from manifesto documents.
To scale a dimension from legislative speeches, we have taken an open-ended approach
and applied an unsupervised method. We have limited ourselves in this paper to test for
the “predictive validity” of the extracted Wordfish scale, but one should also validate
the scale through “semantic validity” and “convergent validity” as suggested by
Grimmer and Stewart (2013). Future research could take this venue to examine if the
Wordfish scale obtained from the Japanese legislative speeches really depicts the
government and opposition conflict. As Grimmer and Stewart (2013: 27) cautions, in
speaking of the Wordfish model, that “one should not assume that wordfish output
measures an ideological location without careful validation”, one should certainly
continue to validate the scale from various methods including the manual human-based
coding coupled with reliability test (Krippendorff, 2004) as well as the supervised
computer-assisted method of scaling.
If we take the words of Grimmer and Stewart (2013: 27) seriously when they state
“non-ideological locations that wordfish identifies are quite useful”, we could also
30
extend the discussions of the index of IGO to the context of intra-party politics where
factions fight each other within the same party. Given that many politicians are recorded
in the parliamentary records, we might be able to extract positions of each faction in
LDP or DPJ and such exercises might open up a new research venue in the field of
intra-party politics. The analyses are also not confined to the main session of the
parliament but the words spoken in various committees could also be collected. If one
builds a database for the scaled points for various politicians in various committees, it
would also be of use in future legislative studies and in the research of political parties.
One could also discuss if the dimension extracted in the Japanese Diet is applicable to
other democracies. The fact that such a government and opposition divide intensifies
might be also institutionally conditioned as parliamentary democracies or arena-type of
parliament. Future research could also take a comparative perspective into account and
put the Japanese legislative speeches in a relative perspective. It could also develop into
some measurements of arena type and/or transformative legislatures (Polsby, 1975). As
noted by Krehbiel and Peskowitz (2012), preferences of political actors are the
animating forces of politics. The method employed to derive such preferences can be
affected by the institutional context in which such preferences are captured. When this
is the case, those preferences become "institutionally endogenous". It would thus be
important to investigate such a relevance of institution on the legislative speeches.
31
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