Mr. Rentaro Iida, Ph.D Candidate, Georgetown University

Interest Groups, Party Polarization, and
the Structure of Abortion Debate:
Dynamic Network Analysis of Abortion
Debate 1970-1994
Rentaro Iida
Georgetown University
Prepared for USJI Week Event 5, September 9 th 2010.

A question of party realignment and
interest groups
• How do parties change their issue positions?
– My argument: “A small set of single issue groups and
ideas they advocated had impacts on how parties
stand on a issue.”
– Case: Over the past three decades, the Republican
party and Democrat party have become increasingly
divided on the abortion issue.
– Theory & method: “Networks”

Why should we care?
• Arguments about a few political elites including
interest groups with ideological motives, that
doesn’t necessarily have direct ties to mass public,
have become overrepresented in the US politics
(cf. Skocpol 2004).
• They may be undermining representative
democracy by skipping party (electoral) process,
causing American politics to be polarized. (cf.
Fiorina et al. 2005, Crenson and Ginsberg 2002)

What is a party? How should we understand interactions
between interest groups and political parties?
• Existing Theories
– Coalitions of politicians who is seeking office, and the
institutions which makes the coordination easy (cf.
Aldrich 1995).
– Parties as coalitions of interest groups (Cohen et al.
2008; Bawn et al. 2007)
– Parties as networks (Masket et al. 2009, Koger et al.
2009)
• However, a very few empirical works on party
realignments conceptualizing parties as networks.

Challenges on data
• Data on interest group activities are extremely
hard to collect in general.
• Conventional empirical strategies
– Uses of various surveys and/or congressional roll calls
• There are very few data on party activities
involving diverse set of actors.
• The conventional empirical strategies tend to
require scholars to focus on one set of actors at a
time.

Which set of actors moved first?

Alternatives: Network Analysis &
Theory
• Many interesting changes in party politics do not start
with what’s changing within one set of actors, but
what’s happening between different types of actors.
• Party is a network among diverse set of actors.
– Theory: Therefore, “what parties stand for” develops
through intentional “brokering” efforts between interest
groups and public figures like Presidents and legislators.
• Network analysis: a tool to visualize and quantify such
structures.
– Treating the abortion debate as a dynamic network.

Data construction
• Using content analysis data gathered by Ferree, Gamson, Gerhard, and Rucht
(2002) on the development of abortion discourse from 1962 to 1994, I was able to
build such network data. They have looked sample of New York Times and LA
Times identified eight “frames” as well as 315 subsets of idea-elements, such as
“abortion is murder” and “women have a right to self-defense” spoken by over
2000 different political actors including journalists, interest groups, politicians
nested in 128 different organization.

What should we expect from the data?
• We should see more networking activities (i.e.
idea sharing activities) over time.
• We should see more networking activities across
different types of actors over time.
• Interest groups of both side should first become
central in the discourse network.
• Politicians other actor should become central in
the networks later.
• We should see more meaningful clusters of actors
developing over time.

speaker network 1970-75
speaker network 1989-94

Count of Ties at Individual Speaker Level (1970-1994)

Count of ties at organizational category level (1970-1994)

Eigenvector Centrality
• A measure about how much a particular node
is connected to well-connected nodes.
– Applications for webpages, congressional speech
etc.
– Tells you about how much control you have for the
network.

Community detections, and
modularity
Identify which actors tend to
share idea-together and group
them into “communities”.
Modularity = (number of ties
within community)- (expected
value of such ties)
e.g. An application in measuring
polarizations in Congress.

Conclusions
• We should theorize party realignment as evolutions of
networks containing diverse set of actors.
• In the case of abortion, interest groups seemed to had a
first-mover advantage in shaping what will be discussed in
media, the politicians and groups with broader focus later
adopted the same kind of language to discuss the abortion.
• In order for an issue to become an salient party cleavage, a
single issue groups has to involve diverse set of people.
Interest
groups?
Polarization of
Media discourse