# QUEUE-20 — Effective independent names in the 50-ETF book (no qrun)

**Status:** QUEUED · **Priority:** P2 · **Effort:** ad-hoc script under `book/data/`

## Hypothesis (settle)
The 50-ETF book has only ~4 effective independent names (CLAIMS.md HYPOTHESIS,
chat-derived eigenvalue analysis, pre-reset). This is a concentration/diversification
claim with direct sizing relevance; verify it on the clean lake.

## Method (persist everything under `book/data/evidence/q20-effective-names/`)
1. Load the 50-ETF panel 1d returns from the lake for the test window 2026-01-04..2026-08-10.
2. Standardize returns; compute the correlation matrix and its eigendecomposition.
3. Count eigenvalues above the Marchenko–Pastur bound (N=50, T≈150) and report the
   cumulative-variance share of the top k components.
4. Effective-rank measures: participation ratio `(Σλ)² / Σλ²` and cumulative 80%
   variance count.
5. Write `eigenanalysis.csv` + a one-page summary.

## Acceptance
- If effective rank ≈ 4 (top-4 explain ~80%+ variance), the concentration claim is
  PROVEN and feeds chapter 08 sizing guidance (why topk 10→20 adds no breadth).
- If effective rank is much larger, mark the claim REFUTED.