Individual-based rarefaction and richness sampling
For a collection containing N individuals with N_i in each observed species, the expected species count in a uniformly drawn subset of n individuals without replacement is E[S_n]=Σ_i[1−C(N−N_i,n)/C(N,n)].
Key knowledge
For a collection containing N individuals with N_i in each observed species, the expected species count in a uniformly drawn subset of n individuals without replacement is E[S_n]=Σ_i[1−C(N−N_i,n)/C(N,n)]. This standardizes a within-collection sampling comparison. It does not estimate all unseen species or remove spatial and detectability biases automatically.
Values and equations
E[S_n]=Σ_i[1−C(N−N_i,n)/C(N,n)]
- N,N_i,n
- collection size, species-i abundance and subset size individual counts
- S_n
- species count in the drawn subset species count
- C(a,n)
- binomial coefficient counting n-subsets of a objects 1
Conditions and scope
- N>0, integer counts, Σ_iN_i=N,0≤n≤N; C(a,n)=0 when n>a. Sampling units are individuals, rather than quadrats or incidence records.
- Different sampling size, abundance distributions and coverage can give different richness rankings. Observed taxonomic classification and sampling design remain part of interpretation; an expected count is not a guaranteed subset count.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read the original paper abstract's hypergeometric expected-richness expression and explicit distinction between composition parameters. Independently derived each term as one minus the probability of avoiding species i; no claim to have read inaccessible full-paper sections or to extrapolate unseen taxa.
2026-10-10 · Independent AI editorial review: All six exact compact records, equations/variables/conditions and eighteen origin edges, plus actual bounded primary sections/abstracts listed below. This is independent AI editorial review, not laboratory validation or whole-Biology revalidation. Receipt: biology-quantitative-independent-review.1.
Entry details
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- uni-bio-rarefaction-sampling
- Revision
- core.1
- Structured reference record
- University core expansion