Title:      Using Item Response Theory to Estimate Ideology in
Congress

Authors:    Jonathan Kropko

Entrydate:  2008-06-28 08:47:55

Keywords:   Item Response Theory, Congress, Ideology

Abstract:   I use item response theory (IRT) to estimate latent
ideology from selected roll-call votes in the first session of
the 110th House of Representatives. Votes are selected if they
are divisive, unique, but not wholly explained by party
loyalties. The method is similar to the one employed by Clinton
et al (2004), but does not assume a spatial structure of voting.
The results demonstrate that (1) although Democrats hold a
majority of the seats in the 110th House, a majority of the
members have conservative ideologies, (2) the Republican party
leadership is much more conservative than the Democratic party
leadership is liberal, and (3) that the House is far less
ideologically polarized than DW-Nominate scores would indicate. 

http://polmeth.wustl.edu/retrieve.php?id=761

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