The Post-it switch, made real — two ballots flip and RCV-IRV elects Blue¶
▶ Live on BetterVoting: vote · results ↗ (election 8kg698, Test ID BV2178).
Equal Vote's video "Updated: How does RCV work? — With Post-its!" ends its count with a hypothetical: what if round 2 had eliminated Green (7 votes) instead of Blue (4)? Its answer — all six Green>Blue>Pink ballots land on Blue, and Blue wins 10–9. But RCV-IRV would never do that: it always eliminates the current last place, and Green held 7 votes to Blue's 4. The hypothetical can't be demonstrated on any real tabulator as-is.
This election demonstrates it anyway — with the smallest honest change. Exactly two of the six Green>Blue>Pink voters flip their top two choices (to Blue>Green>Pink; scores 0,4,5,3). Nothing else moves. That's enough to reverse Green's and Blue's round-2 standing, and RCV-IRV then walks straight into the video's scenario for real:
The count, before and after¶
| BV2176/77 (the video) | BV2178 (two ballots flip) | |
|---|---|---|
| Round 1 | Purple 7, Green 6, Blue 4, Pink 3 → Pink out | Purple 7, Blue 6, Green 4, Pink 3 → Pink out |
| Round 2 | Purple 8, Green 7, Blue 4 → Blue out | Purple 8, Blue 6, Green 5 → Green out |
| Final | Purple 9, Green 8 (3 exhausted) | Blue 10, Purple 9 (1 exhausted) |
The final tally — Blue 10, Purple 9 — is digit-for-digit the video's hypothetical. Two voters moved; the RCV-IRV winner flipped from Purple to Blue. The lesson cuts both ways:
- For the video's point: RCV-IRV only discovers Blue's head-to-head strength when Blue's supporters happen to rank Blue first. Blue beat Purple 10–9 in both electorates — but IRV elects Blue in only one of them. The information was always on the ballots; the elimination order determines whether IRV ever reads it.
- For balance: the flip didn't just game IRV's mechanics — it genuinely changed the electorate. In the original profile Blue was in a Condorcet cycle (Green beat Blue 7–4); after the flip Blue beats everyone — Purple 10–9, Green 6–5, Pink 10–3 — an outright Condorcet winner. The two electorates have different consensus answers, and IRV happens to match the consensus only in the second.
Every method, before and after¶
| Method | BV2176/77 (the video) | BV2178 (switch) |
|---|---|---|
| STAR | Blue (scores 46/38/44/44; runoff 10–9 — a Runoff Reversal) | Blue (scores Blue 46, Purple 46, Pink 44, Green 36 — the co-leaders are the finalists; same runoff 10–9) |
| Ranked Robin | Green on BV / Blue in LH (2–1 tie, two ladders) | Blue everywhere — Condorcet winner 3–0, no tie, no ladder |
| RCV-IRV | Purple (9–8) | Blue (10–9) — the video's hypothetical, real |
| Choose-One | Purple (7) | Purple (7 vs 6) — still reading only first choices |
STAR is the only method above whose winner survives the switch — it was already electing the head-to-head favorite in the runoff. Ranked Robin snaps from its knife-edge tie (where two engines defensibly disagree) to unanimity. IRV swings entirely. Choose-One never notices anything happened.
LH engine report (View 2) — the switch RCV-IRV count¶
ROUND 1
Candidate Votes Status
----------- ------- --------
Purple 7 Hopeful
Blue 6 Hopeful
Green 4 Hopeful
Pink 3 Rejected
ROUND 2
Candidate Votes Status
----------- ------- --------
Purple 8 Hopeful
Blue 6 Hopeful
Green 5 Rejected
Pink 0 Rejected
Blank Votes 1 Rejected
FINAL RESULT
Candidate Votes Status
----------- ------- --------
Blue 10 Elected
Purple 9 Rejected
Green 0 Rejected
Pink 0 Rejected
Blank Votes 1 Rejected
And the switch pairwise picture — Blue, clean Condorcet winner:
Round-Robin — every pair, head-to-head (For – Against):
Purple beats Green 9 – 8
Blue beats Purple 10 – 9
Pink beats Purple 12 – 8
Blue beats Green 6 – 5
Green beats Pink 7 – 5
Blue beats Pink 10 – 3
# Candidate W–L–T Copeland Margin Beats
1 Blue 3–0–0 3 +9 Green, Purple, Pink
Winner — Ranked Robin (RCV-RR): Blue
beats every opponent head-to-head — the Condorcet winner.
Files¶
| Race | YAML | _tabulated mirror |
|---|---|---|
| STAR (lead) | page · bv2178_8kg698_star.yaml | txt |
| RCV-IRV | page · bv2178_8kg698_irv.yaml | txt |
| Ranked Robin | page · bv2178_8kg698_ranked_robin.yaml | txt |
| Choose-One | (documented in the STAR mirror's divergence block: Purple) | — |
Frozen BetterVoting export (Election + Ballots + Results): bv2178_8kg698_bv_export.json — BV's stored winners match every LH prediction (STAR / Ranked Robin / RCV-IRV all Blue; Choose-One Purple).
Related: the BV2176 case page · seven ways (BV2177) · is the video fair and balanced? · up: method_comparisons