strata: Stratum names

In openCR: Open Population Capture-Recapture

Stratum names

Description

Extract or replace the stratum names of a capthist object.

Usage

strata(object, ...)
strata(object) <- value

Arguments

object	object with ‘stratum’ attribute e.g. capthist
value	character vector or vector that may be coerced to character, one value per stratum
...	other arguments (not used)

Details

Replacement values will be coerced to character.

Value

a character vector with one value for each session in capthist.

Note

openCR uses the term ‘stratum’ for an independent set of samples, rather like a ‘session’ in secr. Strata offer flexibility in defining and evaluating between-stratum models. The log likelihood for a stratified model is the sum of the separate stratum log likelihoods. Although this assumes independence of sampling, parameters may be shared across strata, or stratum-specific parameter values may be functions of stratum-level covariates. The detector array and mask can be specified separately for each stratum.

For open population analyses, each stratum comprises both primary and secondary sessions of Pollock's robust design ‘joined’ in a single-session capthist object.

The function stratify can be useful for manipulating data into multi-stratum form.

Models are stratified only if the argument stratified of openCR.fit() is set to TRUE. Strata will otherwise be treated as primary sessions and concatenated as usual with join().

See Also

openCR.fit, session, stratify

Examples

  # artificial example, treating years as strata
  strata(ovenCH)

openCR documentation built on Sept. 25, 2022, 5:06 p.m.