P3 manipulated — two voters bury their 4th choice and STAR elects their favourite¶

Generated from p3_manip_star.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: Edinburgh

Scenario¶

STAR's turn to fail, on the same profile and cheaply. The two sincere Edinburgh>Cork>Athens>Dublin>Bergen voters score their 4th choice Dublin a 0 instead of a 2 — one number each, on one candidate, with their own favourite still a 5 and no favourite betrayal anywhere. Dublin's total drops 23 to 19, which knocks Dublin out of the finalists entirely; the runoff becomes Edinburgh vs Cork and Edinburgh wins 5-2. The two manipulators have replaced Dublin with Edinburgh, their FAVOURITE. This is burial, and it is the honest counterweight to the Copeland and Borda manipulations on this page: Gibbard-Satterthwaite guarantees every reasonable method is manipulable, and that includes both methods this library advocates.

Ballots¶

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

Athens,Bergen,Cork,Dublin,Edinburgh
2:3,0,4,0,5
3:0,3,2,5,4
2:5,4,3,2,0

What the engine says¶

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

[Divergence from STAR]
  STAR                   = Edinburgh
  Choose-One (Plurality) = Dublin   (differs from STAR)
  RCV-IRV                = Dublin   (differs from STAR)
  Approval               = Bergen   (differs from STAR)
  Note: no ballots had tied scores, so RCV-IRV vs STAR here is a genuine
        method difference, not a tie-breaking artifact.
  Note: Ranked Robin (RCV-RR) agrees with STAR, so RCV-IRV is the lone
        outlier — the classic center-squeeze signature.
  Full round-by-round reports (generated for review):
  RCV-IRV rounds: cases_tabulated/p3_manip_star_RCV-IRV_tabulated.txt

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

[STAR Voting]
 Tabulating 7 ballots.
Count × Athens,Bergen,Cork,Dublin,Edinburgh
    3 ×      0,     3,   2,     5,        4
    2 ×      3,     0,   4,     0,        5
    2 ×      5,     4,   3,     2,        0

[STAR Voting: Scoring Round]
 The two highest-scoring candidates advance to the next round.
   Edinburgh     -- 22 -- First place
   Cork          -- 20 -- Second place
   Dublin        -- 19
   Bergen        -- 17
   Athens        -- 16
 Edinburgh and Cork advance.

[STAR Voting: Automatic Runoff Round]
 The candidate preferred in the most head-to-head matchups wins.
   Edinburgh     -- 5 -- First place
   Cork          -- 2
   Equal Support -- 0
 Edinburgh wins.
   Runoff math:
     7  ballots cast
   − 0  Equal Support (no preference between the two finalists)
     ─
     7  voters with a preference  (majority = 4)
           Edinburgh 5 (71%)  ·  Cork 2 (29%)

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

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
                  |     Athens    |    Bergen    |   * Cork     |    Dublin    | * Edinburgh  |
-----------------------------------------------------------------------------------------------
         Athens > |      ---      |  4 - 0 - 3   |  2 - 0 - 5   |  4 - 0 - 3   |  2 - 0 - 5   |
         Bergen > |   3 - 0 - 4   |     ---      |  5 - 0 - 2   |  2 - 2 - 3   |  2 - 0 - 5   |
         * Cork > |   5 - 0 - 2   |  2 - 0 - 5   |     ---      |  4 - 0 - 3   |  2 - 0 - 5   |
         Dublin > |   3 - 0 - 4   |  3 - 2 - 2   |  3 - 0 - 4   |     ---      |  5 - 0 - 2   |
    * Edinburgh > |   5 - 0 - 2   |  5 - 0 - 2   |  5 - 0 - 2   |  2 - 0 - 5   |     ---      |

[Condorcet Winner]
  No Condorcet winner (majority cycle: Athens > Bergen > Cork > Athens)

[Score Distribution] (how many ballots gave each star rating)
                Score
Candidate  5  4  3  2  1  0  | Total   Avg
Athens     2  0  2  0  0  3  |    16   2.3
Bergen     0  2  3  0  0  2  |    17   2.4
Cork       0  2  2  3  0  0  |    20   2.9
Dublin     3  0  0  2  0  2  |    19   2.7
Edinburgh  2  3  0  0  0  2  |    22   3.1

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/manipulability_p3/cases/p3_manip_star.yaml

P3 manipulated — two voters bury their 4th choice and STAR elects their favourite¶

Scenario¶

Ballots¶

What the engine says¶

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

See also¶