Jana Kunicova and Thomas Frederick Remington, "Mandates, Parties and Dissent: Effect of Electoral Rules on Parliamentary Party Cohesion in the Russian State Duma, 1994-2003," Party Politics, 14 (September, 2008), 555-574.

First paragraph:
Party cohesion in legislative politics remains a topic of considerable scholarly interest and substantive importance (Bowler et al., 1999; Hazan, 2003). Analyzing its sources, however, remains a challenge. Until recently, it was difficult to separate the effect of electoral institutions from the workings of legislative parties and rules, constitutional-level arrangements and political context in answering this question. When all members of a national legislature have identical electoral mandate types, it is difficult to isolate the impact of the electoral system in inducing disciplined behavior on the part of members of legislative parties from other features of the national political system.

Figures and Tables:

Table 1. Electoral results (PR) and factional composition of the Russian State Duma, 1994-2003

Table 2. Factions admissible for analysis: number of SMD and PR members

Table 3. Effect of mandate and faction membership on dissent over three Duma convocations

Table 4. Dissent in the Third Duma: controlling for alternative explanations

Last paragraph:
In sum, our main finding is that the bifurcated nature of legislative factions influences levels of voting cohesion across deputies within the same factions. Still, this effect is modest by comparison with faction-level influences such as ideology, as well as, presumably, system-level characteristics such as the constitutional balance of parliamentary and executive power and the nature of the country's party system. Nevertheless, the reality of mandate differences within factions must influence their own internal dynamics as well as their relations with other institutional actors.