Legislative reciprocity: Using a proposal lottery to identify causal effects
Legislative reciprocity: Using a proposal lottery to identify causal effects (DOI: https://doi.org/10.1017/psrm.2025.10032) was written by Semra Sevi and Donald P. Green in 2025. It was published in Political Science Research and Methods.
Authors study PMBs in the Canadian Parliament. Specifically, they look at whether members trade votes by seconding each others' proposals.
The authors argue that there are few opportunities for MPs to credit claim, following from Mayhew's model of legislator behavior. PMBs therefore represent a rare and valuable asset. Fundamentally, they analyze if having the opportunity to propose a bill makes one more likely to second another bill.
The authors collect parliamentary data covering PMB proposers and seconders from 2004 to 2021. They join on demographic data concerning the members themselves.
The independent variable of interest, opportunity to propose a bill, is not a binary variable. Readings are scheduled as available, so a member's place in order is effectively a probability of having that opportunity. The authors adjust this to create a 'relative' place in order. At the same time, only proposals that got scheduled are represented in the data set.
Note that up to 20 members can second a bill by registering their support with the clerk. This only affected 27 bills in the data set.
There is no significant evidence that members trade votes.