Comparing Electoral Systems for the Massachusetts Legislature

We are proud to announce the release of a new modeling and research report, in partnership with New America, a public policy think tank with a strong profile in the democracy space. Together, we studied the possible implications of systems change in the way the Massachusetts legislature is elected.

We have applied a suite of statistical models to test alternative electoral systems, with a particular focus on STV — multi-member districts using ranked choice voting.

Our models allow us to vary many assumptions about voter behavior. Do voters behave impulsively, filling out their ballots from top to bottom according to their group’s general candidate preferences? Or do they behave deliberatively, examining a ranking and deciding on whether to make swaps before submitting their vote? Are they likely to vote short ballots, listing just a few candidate names and leaving the rest blank, as voters often do in the ranked choice elections in Cambridge, MA?

We also incorporate different assumptions about the tendency for racial/ethnic groups to vote cohesively for distinct sets of candidates versus crossing over to vote for those who are majority-preferred. Likewise, we vary assumptions about partisan voting behavior.

Our results are extremely encouraging in terms of the tendency for STV to produce proportional outcomes for Massachusetts voters. One striking finding is that STV (the multi-member form of ranked choice) would behave very differently from IRV (ranked choice where one candidate is elected per district), even if voter preferences are kept exactly constant.

You can download our report here, and check out the summary brief from New America here.