# Task IV-2 Kendall Tau Rank Stability

## Per-scene Results
### bonsai (N=10 methods)
| pair | tau | p-value |
|---|---|---|
| default vs seed1 | 0.7778 | 0.0009 |
| default vs seed2 | 0.7333 | 0.0022 |
| seed1 vs seed2 | 0.9556 | 0.0 |

**median tau:** 0.7778

### Lego (N=8 methods, erankgs excluded)
| pair | tau | p-value |
|---|---|---|
| default vs seed1 | 0.8571 | 0.0017 |
| default vs seed2 | 0.8571 | 0.0017 |
| seed1 vs seed2 | 1.0 | 0.0 |

**median tau:** 0.8571

## Global
**median tau across 2 scenes × 3 pairs (6 values):** 0.8571

## Interpretation
tau=1.0 = perfectly stable; tau<0.7 = unstable (threshold for §4.1 claim)

## Top 3 Most Unstable Methods
| method | rank range | min rank | max rank |
|---|---|---|---|
| minisplatting | 6 | 2 | 8 |
| analyticsplatting | 5 | 2 | 7 |
| vanilla_3dgs | 3 | 2 | 5 |

## §4.1 Claim Check
- "方法排名在 3 seeds 上不稳定": **[SUPPORTED]**
  (至少一个 scene median tau < 0.9)