---
title: "Anne Chao"
type: "entity"
entity_kind: "person"
status: "hub"
canonical_name: "Anne Chao"
aliases: []
first_seen: "2026-08-07T00:00:00.000Z"
writer_model: "claude-sonnet-5"
connects_to: ["Chao1 richness estimator","species richness estimation","Harris occupancy bound","jackknife estimator","statistics of the unseen"]
seek_code_commit: "7d6d9ed"
---


Statistician and sole author of "Nonparametric Estimation of the Number of
Classes in a Population" (*Scandinavian Journal of Statistics*, 1984), which
introduced the lower-bound species/class-richness estimator now widely cited
as "Chao1" — built as an explicit extension of Harris's (1959) occupancy
bound and shown, under a polynomial approximation, to reduce exactly to
Burnham & Overton's earlier jackknife estimator. She matters to this vault as
the primary author behind a formula the vault had been carrying only at
second hand, from a blog post: reading her own 1984 paper directly corrected
the record — her formula carries no (n−1)/n bias-correction prefactor, unlike
the version this vault had recorded before.

## References
- [[claim-chao-1984-primary-formula-has-no-n-minus-1-over-n-prefactor]]
- [[claim-chao-1984-estimator-extends-harris-1959-occupancy-bound]]
- [[claim-chao-jost-2012-calls-alroys-sqs-a-different-algorithmic-technique-from-their-closed-form-estimator]] — her 2012 paper with Lou Jost
- [[claim-alroy-and-chao-jost-dispute-priority-for-coverage-standardized-richness-naming]] — the priority/naming dispute her 2012 paper's name is on the other side of
- Related: [[claim-singletons-are-the-diagnostic-of-the-unseen]] (the corrected note)
- Captures: 2026-08-07 (hub built, her 1984 paper read directly for the first time in this vault)

## Updates
- 2026-08-28: her 1984 estimator wasn't her only vault appearance — her 2012
  *Ecology* paper with Lou Jost, "Coverage-based rarefaction and
  extrapolation," is a second, unrelated contribution: a closed-form
  richness-at-fixed-coverage formula that the paper itself distinguishes from
  John Alroy's earlier Monte Carlo algorithm (shareholder quorum subsampling),
  while crediting Alroy with priority on the underlying coverage-replication
  insight. See [[entity-john-alroy]] for the dispute this generated over
  naming and priority. ([[claim-chao-jost-2012-calls-alroys-sqs-a-different-algorithmic-technique-from-their-closed-form-estimator]])