Use Schnabel Estimate when you need to estimate population size from a documented two sample Schnabel census. Enter Caught in session one, Caught in session two, and Recaptures total using the definitions and units below so the result can be reproduced.

Caught in session one

An integer count or setting greater than or equal to 1, expressed in individuals.

Caught in session two

An integer count or setting greater than or equal to 1, expressed in individuals.

Recaptures total

An integer count or setting, expressed in individuals.

The published tool contract uses this rule: Estimate population size from a documented two sample Schnabel census.

Schnabel estimate

The calculated schnabel estimate in individuals.

The output is an estimate tied to the stated model and coefficients; it is not a direct measurement and should retain that label when reported.

Retain the original Caught in session one, Caught in session two, and Recaptures total values and their units alongside the result. Lincoln Petersen Estimator is useful when you instead need to estimate population size from two capture sessions with the Lincoln Petersen index. Chao1 Estimator provides another view by helping you estimate total species richness from singletons and doubletons in a single sample using the Chao1 estimator.

• Lincoln Petersen Estimator

  Estimate population size from two capture sessions with the Lincoln Petersen index.

• Chao1 Estimator

  Estimate total species richness from singletons and doubletons in a single sample using the Chao1 estimator.

• Chao2 Estimator

  Estimate total species richness from incidence data across samples using the Chao2 estimator.