Title:      Non-ignorable abstentions in roll call data analysis

Authors:    Guillermo Rosas, Yael Shomer

Entrydate:  2008-07-02 03:57:23

Keywords:   ignorability, IRT model, roll call data, legislative
voting

Abstract:   How should we deal with abstentions in roll-call
data analysis? Abstentions are very common in decision-making
bodies around the world, and very often obey to a strategic
rationale. Methods to recover ideal points from roll-call
datasets -- such as Nominate and MCMC IRT -- are based on
assumptions about the ignorability of the abstention- generating
mechanism. However, the strategic character of abstentions makes
the assumption of ignorability difficult to meet in practice. We
discuss different abstention-generating
mechanisms to understand the conditions under which they may be
deemed
ignorable, and extend the MCMC IRT model so as to incorporate
information from
abstention patterns into inference about legislators' ideal
points.

http://polmeth.wustl.edu/retrieve.php?id=767

**********************************************************
             Political Methodology E-Mail List
   Editors: Melanie Goodrich, <[log in to unmask]>
            Delia Bailey, <[log in to unmask]>
**********************************************************
        Send messages to [log in to unmask]
  To join the list, cancel your subscription, or modify
           your subscription settings visit:

          http://polmeth.wustl.edu/polmeth.php

**********************************************************