This study presents a Bayesian spatial voting analysis of the Colombian Senate during the 2006-2010 legislative period, leveraging a newly constructed roll-call dataset comprising 147 senators and 136 plenary votes. We estimate legislators' ideal points under two alternative geometric frameworks: A traditional Euclidean model and a circular model that embeds preferences on the unit circle. Both models are implemented using Markov Chain Monte Carlo methods, with the circular specification capturing geodesic distances and von Mises-distributed latent traits. The results reveal a latent structure in voting behavior best characterized not by a conventional left-right ideological continuum but by an opposition-non-opposition alignment. Using Bayesian logistic regression, we further investigate the association between senators' ideal points and their involvement in the para-politics scandal. Findings indicate a significant and robust relationship between political alignment and para-politics implication, suggesting that extralegal influence was systematically related to senators' legislative behavior during this period.

翻译：本研究基于新构建的唱名表决数据集（包含147名参议员和136次全体会议表决），对2006-2010立法会期哥伦比亚参议院进行贝叶斯空间投票分析。我们在两种几何框架下估计立法者的理想点：传统欧几里得模型与将偏好嵌入单位圆的环形模型。两种模型均采用马尔可夫链蒙特卡罗方法实现，其中环形模型捕捉测地线距离和服从冯·米塞斯分布的潜变量。结果显示，投票行为中的潜在结构并非由传统的左右意识形态连续体所表征，而是以反对派-非反对派联盟为最佳特征。通过贝叶斯逻辑回归，我们进一步探究了参议员理想点与其卷入准政治丑闻之间的关联。研究结果表明，政治联盟与准政治牵连存在显著且稳健的相关性，暗示着此期间法外影响力与参议员的立法行为存在系统性关联。