In European parliamentary democracies political parties control candidate selection, maintain cohesion in the legislature and support governments. In addition to these classic functions, parties also organise the legislature delegating power to legislators, specifically as committee chairs and party coordinators. Delegation is inherently dangerous, involving potential agency loss. Parties, however, have ex-ante and ex-post institutional mechanisms to deal with agency problems. In this paper, a case study is made of the Portuguese legislature, arguing that parties make use of their pivotal role in selecting legislators as committee chairs and party coordinators to keep tabs on legislators to thwart shirking from the party line. This paper finds that political parties use incumbency as an ex-ante screening mechanism of committee chairs and party coordinators in looking for reliable signals of past behaviour to decrease uncertainty. Additionally, evidence suggests that extraparliamentary party structure is used as an institutional arena for ex-post control of party coordinators.
Large-scale surveys typically exhibit data structures characterized by rich mutual dependencies between surveyed variables and individual-specific skip patterns. Despite high efforts in fieldwork and questionnaire design, missing values inevitably occur. One approach for handling missing values is to provide multiply imputed data sets, thus enhancing the analytical potential of the surveyed data. To preserve possible nonlinear relationships among variables and incorporate skip patterns that make the full conditional distributions individual specific, we adapt a full conditional multiple imputation approach based on sequential classification and regression trees. Individual-specific skip patterns and constraints are handled within imputation in a way ensuring the consistency of the sequence of full conditional distributions. The suggested approach is illustrated in the context of income imputation in the adult cohort of the National Educational Panel Study.