STAR's residual split — a coalition bullet-votes itself apart¶

Generated from 05a_residual_split_bullet-voting.yaml — do not edit by hand. Regenerate: python STARVote_LH_tabulation_engine/tools_adam/scripts/build_yaml_pages.py.

Method: STAR (single winner) · 1 seat · Expected winner: Cara

Scenario¶

The honest caveat to "STAR ends vote-splitting": it ends the FORCED kind. A faction can still split ITSELF if it refuses to use the score ballot.

Ada and Ben are on the same side (60 voters); Cara is the opponent (40). Here the Ada/Ben side bullet-votes tribally — Ada-fans give Ben a 0, Ben-fans give Ada a 0 — instead of scoring their ally honestly. Scores: Ada 175, Ben 125, Cara 200. Cara grabs a finalist slot on a split field and wins the runoff, even though 60% preferred that side. STAR did not rescue a split the voters inflicted on themselves: the residual lives only in the top-two runoff.

The cure is in their hands — see 05b_residual_split_expressive-fix.yaml, where the SAME factions score their ally even a 3 and STAR elects the majority side. Deep dive: 07_Concepts/residual_vote_splitting.md

Parameters (from the YAML)¶

blocs:
  Allies: [Ada, Ben]

Ballots¶

Row 1 = candidate names; each later row is one voter's 0–5 scores (a N × prefix = N identical ballots).

Count:Ada,Ben,Cara
35:5,0,0   # Ada-fans bullet-vote — refuse to score their ally Ben
25:0,5,0   # Ben-fans bullet-vote — refuse to score their ally Ada
40:0,0,5   # Cara bloc (the minority side)

What the engine says¶

The count, step by step — the rounds and how the winner is reached:

[Vote-splitting check]
  Choose-One first choices: Cara 40, Ada 35, Ben 25
  Plurality winner: Cara (40, 40.0%)
  Bloc 'Allies' = Ada, Ben: combined 60 (60.0%); winner Cara is OUTSIDE it.
  => VOTE SPLITTING: the 'Allies' bloc is an outright majority (60 vs Cara's
     40) but split across 2 candidates, so Cara won Choose-One. STAR elected
     Cara.

--- STAR Voting Method (single winner) ---

[STAR Voting]
 Tabulating 100 ballots.
Count × Ada,Ben,Cara
   40 ×   0,  0,   5
   35 ×   5,  0,   0
   25 ×   0,  5,   0

[STAR Voting: Scoring Round]
 The two highest-scoring candidates advance to the next round.
   Cara          -- 200 -- First place
   Ada           -- 175 -- Second place
   Ben           -- 125
 Cara and Ada advance.

[STAR Voting: Automatic Runoff Round]
 The candidate preferred in the most head-to-head matchups wins.
   Cara          -- 40 -- First place
   Ada           -- 35
   Equal Support -- 25
 Cara wins.
   Runoff math:
     100  ballots cast
   −  25  Equal Support (no preference between the two finalists)
     ───
      75  voters with a preference  (majority = 38)
           Cara 40 (53%)  ·  Ada 35 (47%)

[STAR Voting: Winner — STAR Voting Method (single winner)]
 Cara

Full audit — preference matrix, Condorcet, and score distribution¶

--- Runoff (Preference) Matrix ---
Head-to-head / pairwise comparison
Legend: For - Equal Support - Against
        * indicates Top 2 Finalist
                 |    * Ada     |     Ben     |   * Cara    |
-------------------------------------------------------------
         * Ada > |     ---      |35 - 40 - 25 |35 - 25 - 40 |
           Ben > | 25 - 40 - 35 |    ---      |25 - 35 - 40 |
        * Cara > | 40 - 25 - 35 |40 - 35 - 25 |    ---      |

[Condorcet Winner]
  Condorcet Winner: Cara — matches the STAR winner

[Condorcet Loser]
  Condorcet Loser: Ben — loses every head-to-head matchup

[Score Distribution] (how many ballots gave each star rating)
                   Score
Candidate   5   4   3   2   1   0  | Total   Avg
Ada        35   0   0   0   0  65  |   175   1.8
Ben        25   0   0   0   0  75  |   125   1.3
Cara       40   0   0   0   0  60  |   200   2.0

Everything in one file: the _tabulated mirror (regenerated on every run; every analysis forced on).

Run it yourself:

python STARVote_LH_tabulation_engine/starvote_larry_hastings.py method_comparisons/split_voting/_main/05a_residual_split_bullet-voting.yaml