Nielson is a scholar of American elections, political behavior, voter turnout and participation, and election administration. Her current research examines how voter demographics affect their likelihood of voting in elections, the role that election laws play in determining turnout and confidence in elections, and how congressional elections affect policy making. Her research has been funded by the National Science Foundation. She holds a PhD in political science from the University of California, San Diego and did postdoctoral work at the University of San Diego.
Argues that some voters have deep concerns about voter privacy that are not easily assuaged. Utilizes data from a field experiment and the 2008 Cooperative Congressional Election Study and demonstrates that those who go against their community's descriptive political norm or majority are more sensitive to issues of privacy and harder to reassure that voting conditions will safeguard the confidentiality of their choices.
Demonstrates that the ideology of congressional primary electorates affects the ideology of the elected nominee. Argues that extreme Republicans are more likely to win their party’s primary, but Republican and Democratic candidates are responsive to different segments of their electoral constituencies.