Title:      Partisans without constraint:  Political polarization and
trends in American public opinion

Authors:    Andrew Gelman, Delia Baldassarri

Entrydate:  2007-07-06 17:51:04

Keywords:   issue alignment, partisanship, polarization

Abstract:   Political polarization is commonly measured using the
variation of responses on an individual issue. By this measure,
research has shown that---despite many commentators' concerns about
increased polarization---Americans' attitudes have become no more
variable in recent decades. What has changed in the electorate is 
its level of partisanship. 

We define a new measure of political polarization as increased
correlations in political attitudes and we distinguish between issue
partisanship---the correlation of issue attitudes with party ID or
ideology---and issue alignment---the correlation between pairs of
issues. Using the National Election Studies (1972-2004), we find
issue alignment to have increased by only 2 percentage points in
correlation per decade. Issue partisanship has increased more than
twice as fast, thus suggesting that changes in people's attitudes
correspond more to a re-sorting of party labels among voters than to
greater constraint on issue attitudes. Since parties are more
polarized, they are now better at sorting individuals along
ideological lines. 

Increased issue partisanship, in a context of persistently low issue
constraint, might give greater voice to political extremists and
single-issue advocates, and amplify dynamics of unequal
representation.

http://polmeth.wustl.edu/retrieve.php?id=698