How Issue Stance Scores Work
A technical explanation of how legislator stance scores are derived from voting records on specific policy issues in the South Dakota 101st legislative session.
What Are Issue Stances?
Each legislator on this site has scores on specific policy issues, derived entirely from their voting record. Scores range from -1 (consistent opposition) to +1 (consistent support) on each issue.
Issues are defined as directional action phrases. For example, a score of +0.6 on “reduce property tax rates” indicates that the legislator has generally voted in favor of bills that reduce property taxes. A score of -0.4 on the same issue indicates the opposite pattern.
These scores describe voting behavior — how a legislator has voted on bills touching each issue. They do not represent personal beliefs, campaign positions, or intent.
The Issue Taxonomy
The system uses 84 canonical policy issues organized under 25 topic categories. Each issue is a directional action phrase:
Topics vary in breadth. Healthcare & Medicaid and Business Regulation each contain 5 issues, while topics like Tribal Relations and Firearms contain 2.
Top 12 of 25 topics by number of canonical issues. Total: 84 issues.
How Bills Are Scored
Each bill is analyzed to identify 1 to 5 relevant policy issues from the canonical list. For each identified issue, two values are assigned:
- Stance (-1.0 to +1.0): What a Yea vote on this bill means for this issue. Positive = supports the action, negative = opposes it.
- Relevance (0.0 to 1.0): How central this issue is to the bill. A bill primarily about property taxes would have high relevance for tax issues and lower relevance for tangentially related issues.
Worked example: a hypothetical property tax relief bill
A Yea vote on this bill indicates support for reducing property taxes (positive stance) but opposition to reducing government spending (negative stance, since the bill reduces revenue).
Procedural bills (appointments, commemorations, scheduling) receive no stances and do not affect legislator scores.
How Legislator Scores Are Computed
For each legislator and each issue, the system aggregates their Yea/Nay votes on all bills that touch that issue:
- Vote direction: +1 for Yea, -1 for Nay.
- Recency weighting: Current-session votes receive more weight than prior-session votes, so scores reflect recent behavior.
- Confidence: Based on the number of scored votes for that issue. A legislator needs at least 15 relevant votes for full confidence; fewer votes produce a lower confidence value.
Data flow from bill text through issue identification and vote records to per-legislator stance profiles.
Reading the Stance Profile
On each legislator's page, stances are displayed as a collapsible topic grid. Each topic row shows the topic's average score and can be expanded to reveal individual issue scores within that topic.
Color scale
Scores are displayed on a color scale: green indicates support (positive scores), gray indicates neutrality (scores near zero), and red indicates opposition (negative scores). Color opacity reflects confidence — bolder colors represent scores backed by more voting data.
Topic averages
The score shown for each topic heading is the mean of all issue scores within that topic. Expanding a topic reveals the individual issue scores that compose the average.
Limitations & Methodology Notes
- Voting behavior, not beliefs. Scores reflect how a legislator voted, not their personal views or stated positions. A legislator may vote against a bill for procedural reasons unrelated to the policy issue.
- Low-coverage issues. Some policy issues appear in few bills during a session. Scores on these issues have lower confidence and may shift as more relevant bills are voted on.
- Absent and voice votes. Only recorded Yea and Nay votes are captured. Absent votes and voice votes (where individual positions are not recorded) are excluded.
- AI classification. The system uses AI (Claude) to identify which policy issues each bill addresses and to assign stance and relevance scores. This classification is probabilistic and may occasionally miscategorize a bill's relationship to an issue.
- Session scope. Scores draw from the 2025 and 2026 South Dakota legislative sessions. Legislators who served only one session have less voting data available.
Stance profiles are visible on each legislator's page. For details on how these scores are used to predict votes, see How We Predict Votes.