February 5, 2023
Tomoko Matsumoto from Tokyo University of Science 234
Investigation of the Role of Policy Disagreements in Party Switching, Splits and Mergers, using a Japanese example by Professor Motsomoto.

Split in a major opposition party of Japan In 2017 resulted in a dramatic shift in the Japanese party system. This split turned the Japanese election into a three-way contest. It was said that long-dormant policy disagreements prompted the legislators to switch parties. Researchers from Japan have recently tried to understand the scenario by analysing the post-electoral expert survey data.

Their findings of the latest research revealed the reasons for the separation and also the basis for party cohesion. This may offer some valuable insights into party unity and cohesion. Though the transformation of party politics in Japan has been marked by an array of sensational events since older days. Japanese politics has witnessed many colours, from the dominance of the Liberal Democratic Party (LDP) to party fragmentation. But the question remains unanswered, why do the legislatures switch parties?

Tomoko Matsumoto from Tokyo University of Science  3424

Political analysts suggest that this happens for a number of reasons. It includes policy considerations. “Party switching” results in payoffs which are closely linked to electoral and party systems. It may lead to a shift in the dynamics of party competition.

Japan witnessed party switching before the 2017 election. A new party, “Hope,” came up and its founding leader aggressively politicized an inactive debate around the defence policy. Several legislatures were persuaded to join the Hope party. It resulted in the collapse of the largest opposition group, “Minshin,” and three parties were formed. However, there was no explanation why the long-dormant disagreement culminated in such a severe falling-out.

A research led by the Junior Associate Professor Tomoko Matsumoto from Tokyo University of Science tries to explain why the individual legislators switch parties. This Japanese research group consisted of Associate Professor Hiroki Kubo of Meiji Gakuin University, and Professor Kentaro Yamamoto of Hokkai-Gakuen University.

Tomoko Matsumoto, Hiroki Kubo, and Kentaro Yamamoto examined the responses on “issue position” and the “salience of party policies” from an expert survey. This survey was conducted shortly after the 2017 general elections in Japan. Finally, this seminal study was recently published in the Japanese Journal of Political Studies.

The frequent split in the opposition parties have created uncertainty among the voters. By analysing the expert survey, our effort was to understand the structure of policies of the opposition parties in Japan.

Dr. Matsumoto

The group started their study by assessing the expert responses using the “differential-item functioning (DIF)” analysis of “Aldrich-McKelvey” scaling. The “Blackbox transpose” was employed next, scaling to examine the multidimensional nature of the issue stances. This study raised one important point. It is that traditional DIF analysis assumes diversity in responses is due to limitations of perceptions and biases.

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Study group found some interesting things in their study. Firstly, the diversity in this case resulted in the parties being unable to discern and convey their policy positions. To correct this, a new version of the DIF analysis was required. “We can say, the importance of using responses after rectification was reaffirmed,” reveals Dr. Matsumoto. “This was a huge revelation as online surveys are increasingly being used for scientific research,” she adds.

The results of Matsomoto’s study revealed that there was a strong discord among the splinter parties over the defence policy of Japan. However, they had similar opinions on the issues of environment, decentralization, and other policies. Most likely, this may have been the foundation for the unity of the main opposition camp. Furthermore, DIF analysis reveals considerable differences in expert responses on the relevance of defence policy. It can be said that the rapid politicization of defence policy may have contributed to its relevance. This finally led to the split.

Although the study suggests that the major opposition in Japan had a split approach for the defence policy, the splitted opposition still agreed on environmental and decentralization policies. These findings will go a long way and help in improving our understanding of the political structures. Though this may not be the final conclusion. There are so many other factors which lead to splits in parties, including opportunism and greed.

References:
Title of original paper: Party Switching and Policy Disagreement: Scaling Analysis of Experts’
Judgement
Journal: Japanese Journal of Political Studies
DOI: https://doi.org/10.1017/S1468109922000160

* Tomoko Matsumoto is a Junior Associate Professor at Tokyo University of Science. In 2016, she received her PhD in Politics from The University of Tokyo. 

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