  This paper applies Bayesian methodologies to characterize the legislative
behavior of the Colombian Senate during the period 2010-2014. The analysis is
carried out through the plenary roll call votes of this legislative chamber. In
addition, parliamentary electoral behavior is operationalized by implementing
the one-dimensional standard Bayesian ideal point estimator via the Markov
chain Monte Carlo algorithms. The results contribute mainly to two points:
political space dimensionality and the identification of pivot legislators. The
pattern revealed by the estimated ideal points suggests a latent
non-ideological trait (opposition - non-opposition) underlying the vote of
deputies in the Senate. Thus, in addition to providing empirical evidence for a
better understanding of legislative policy in Colombia during the period under
analysis, this work also offers methodological and theoretical tools to guide
the analysis of roll call vote data in contexts of unbalanced parliaments (as
opposed to the U.S. parliament), taking the particular case of the Colombian
Senate as a reference.
