Work out species richness instantly with clear inputs, formula shown and shareable results.
Applies the Chao1 estimator, which infers undetected species from the number seen only once or twice in the sample.
Chao1 estimator
Chao1 = S_obs + f1^2 / (2 f2), where f1 is singletons and f2 doubletons; the bias-corrected form is used when f2 is zero
Many species seen once implies the sample is far from saturated, so more species remain undetected.
It is a lower bound on true richness, and it rises as sampling continues until the asymptote is approached.