Kamarck and Podkul, “The 2018 Primaries Project: The demographics of primary voters.” The Brookings Institution. 2018. | Finds that primary electorates are both more extreme and less diverse on multiple dimensions, including race, than general election electorates.

Ferrer et al, “The Effect of Open Primaries on Turnout and Representation.” Bipartisan Policy Center. 2024. | Finds that partisan primary voters are less representative and diverse than general election electorates; on the other hand open primaries tend to be associated with higher and more diverse turnout.

Grose, “Reducing Legislative Polarization: Top-Two and Open Primaries Are Associated with More Moderate Legislators.” Schwarzenegger Institute. 2020. | Finds that Top Two elections in CA decreased partisanship in elected officials.

Macomber, “Nonpartisan Primaries Increase Primary Turnout.” Unite America Institute. 2024. | Finds that primary turnout increases under nonpartisan primaries.

Hall, “State elections, policy choices, and accountability.” Institute for Economic Policy Research, Stanford. 2021. | Finds that legislators operating in more competitive electoral environments are more responsive to voter concerns and display more accountability.

Barton, “California’s Top-Two Primary: The Effects on Electoral Politics and Governance.” Unite America Institute. 2023 | Finds that CA’s transition to Top Two elections was associated with higher voter turnout in elections and less partisan behavior among elected officials.

McGhee & Shore, “Has the Top Two Primary Elected More Moderates?” Perspectives on Politics. 2017. | Finds small but clear positive effects on representation, and decreased partisanship, associated with a switch to Top Two elections; suggests that these effects are strengthened by other changes, like independent redistricting.