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Data - Member Ideology
Voteview
January 22, 2026
Member Ideology Data
The Member Ideology data export contains biographical and ideological information about members of congress for the chamber(s) and congress(es) that were selected.
Quick Link (all congresses, all chambers, CSV format): https://voteview.com/static/data/out/members/HSall_members.csv
Biographical Fields:
- congress: Integer
1+. The number of the congress that this member’s row refers to. e.g.115for the 115th Congress (2017-2019) - chamber:
House,Senate, orPresident. The chamber in which the member served. - icpsr: Integer
1-99999. This is an ID code which identifies the member in question. In general, each member receives a single ICPSR identifier applicable to their entire career. A small number of members have received more than one: this can occur for members who have switched parties; as well as members who subsequently become president. Creating a new identifier allows a new NOMINATE estimate to be produced for separate appearances of a member in different roles. - state_icpsr: Integer
0-99. Identifier for the state represented by the member. - district_code: Integer
0-99. Identifier for the district that the member represents within their state (e.g.3for the Alabama 3rd Congressional District). Senate members are givendistrict_code0. Members who represent historical “at-large” districts are assigned99,98, or1in various circumstances. - state_abbrev: String. Two-character postal
abbreviation for state (e.g.
MOfor Missouri). - party_code: Integer
1-9999. Identifying code for the member’s party. Please see documentation for Party Data for more information about whichparty_codeidentifiers refer to which parties. - occupancy: Integer
1+. ICPSR occupancy code. This item is considered legacy or incomplete information and has not been verified. In general, members receive0if they are the only occupant,1if they are the first occupant,2if they are the second occupant, etc. - last_means: Integer
1-5. ICPSR Attain-Office Code. This is an indicator that reflects the member’s last means of attaining office. This item is considered legacy or incomplete information and has not been verified. Members received1if they were elected in a general election,2if elected by special election,3if directly elected by a state legislature, and5if appointed. - bioname: String. Name of the member, surname first. For most members, agrees with the Biographical Directory of Congress.
- bioguide_id: String. Member identifier in the Biographical Directory of Congress.
- born: Integer. Year of member’s birth.
- died: Integer. Year of member’s death.
Ideological Fields:
- nominate_dim1: NOMINATE first dimension estimate.
- nominate_dim2: NOMINATE second dimension estimate.
- log_likelihood: Log-likelihood of the NOMINATE estimate.
- geo_mean_probability: Geometric mean probability of NOMINATE estimate.
- number_of_votes: Number of votes cast by the member during a given congress.
- conditional: Integer
0-1. A1indicates NOMINATE was estimated conditionally for a given member.0otherwise. Conditional estimation implies that an estimate is provisional and subject to updates when the next full estimation of NOMINATE scores occurs. - nokken_poole_dim1: Nokken-Poole First dimension estimate.
- nokken_poole_dim2: Nokken-Poole Second dimension estimate.
Making use of Ideological Data
We present two main estimates of a legislator’s ideology: NOMINATE
and Nokken-Poole. NOMINATE estimates assume that members occupy a static
ideological position across the course of their career. Nokken-Poole
estimates assume that each congress is completely separate for the
purposes of estimating a member’s ideology. We expect that most users of
our data will primarily make use of the nominate_dim1
field, which reports the first dimension (often interpreted as economic
liberalism-conservatism) of members as estimated by NOMINATE.
For more information on these scores, please see discussion in our journal article:
Boche, Adam, Jeffrey B. Lewis, Aaron Rudkin, and Luke Sonnet. “The new Voteview.com: preserving and continuing Keith Poole’s infrastructure for scholars, students and observers of Congress”. Public Choice 176(1-2). Available online: https://link.springer.com/article/10.1007/s11127-018-0546-0
Citation
To cite this data, please use the following citation:
Lewis, Jeffrey B., Keith Poole, Howard Rosenthal, Adam Boche, Aaron Rudkin, and Luke Sonnet (2026). Voteview: Congressional Roll-Call Votes Database. https://voteview.com/