Phase 5 — Lieberson Null Model Results

Generated: 2026-04-12 00:48 UTC Pipeline step: Phase 5 (null model) — body regenerated from `null_model_summary.json` + `null_model_thresholds.parquet`.

Key Findings

• •**Total name-year rows (thresholds parquet):** 1,950,660
• •**Unique names (summary JSON):** 46,412
• •**Names classified (≥10 SSA years, bucketed):** 46,412
• •**Innovation rate (μ):** 0.050455
• •**N_e (female):** 9,852
• •**N_e (male):** 22,320
• •**Average observed turnover per decade:** 23.4%
• •**Share of name-years beating neutral drift at p95:** 4.57%
• •**Share of name-years beating neutral drift at p99:** 2.83%
• •**Share of name-years beating phonetic null at p95:** 5.27%
• •**Share of name-years beating phonetic null at p99:** 3.74%

Classification Breakdown (table)

Buckets use the share of years (aggregated across sexes) where `beats_neutral_p99` is true, for names with at least 10 distinct SSA years:

Methodology Notes

• •**Parquet columns used:** `name`, `year`, `beats_neutral_p99` on `null_model_thresholds.parquet`.
• •**Year-level beat:** for each `(name, year)`, `beats_neutral_p99` is the logical OR across sex rows for that name-year.
• •**Per-name fraction:** mean of year-level beats over all years with data for that name (among names with ≥10 years).
• •**Bucket thresholds:** `<5%` drift-consistent; `5–19%` partially-cultural; `20–39%` culturally-influenced; `≥40%` strongly-cultural.
• •**Summary metrics** (μ, N_e, turnover, % beating nulls) are read from `null_model_summary.json`.