This dataset is from Voteview, a website by political scientists Keith Poole and Howard Rosenthal that freely provides information on congressional roll call votes in the United States. The data goes back to the first U.S. congress in 1789, and includes votes from both the Senate and the House of Representatives. In addition the the votes themselves, Voteview's datasets include indicators of politicians' ideological positions, which have been estimated using NOMINATE. See also the 'Details' section below.
nominateA tibble with 49,361 observations and 9 variables:
integer variable indicating the number of a member's congress, e.g. 116 for the 116th congress (2019-2021)
character variable indicating the chamber in which a member served, either "House" or "Senate". The value of "President" indicates that it is data for the incumbent President.
character variable indicating the state a member represented
character variable indicating a member's party
character variable in the format "last, first" indicating a member's name
double variable indicating a member's year of birth
double variable indicating a member's year of death
double variable in the range of [-1,1] indicating a member's ideological position on economic matters, also referred to as the 'left-right' spectrum. Lower values indicate left-wing positions, higher values indicate right-wing positions.
double variable in the range of [-1,1] indicating a member's ideological position on societal matters, e.g. LBGT rights or slavery. Lower values indicate anti-establishment positions, higher values indicate pro-establishment positions.
At its core, NOMINATE is a scaling procedure that uses algorithms to arrange politicians in a two-dimensional coordinate system based on their voting behaviour and how they compare to others. The x-axis indicates politicians' positions on ideological matters, and the y-axis indicates positions on societal issues, thereby 'mapping' legislatures. For a detailed explanation of the technical background, see the original paper "A Spatial Model for Legislative Roll Call Analysis" by Poole and Rosenthal (1983).