pChapman: Hypothesis Testing Using the Chapman Estimator

In mbtyers/recapr: Two Event Mark-Recapture Experiment

Description

Approximates a p-value for a hypothesis test of the Chapman estimator by means of many simulated draws from the null distribution, conditioned on sample sizes.

Usage

pChapman(
  estN = NULL,
  nullN,
  n1,
  n2,
  m2 = NULL,
  nsim = 1e+05,
  alternative = "less"
)

Arguments

estN	The estimated abundance. Either this or the number of recaptures (m2) must be specified.
nullN	The abundance given by the null hypothesis
n1	Number of individuals captured and marked in the first sample
n2	Number of individuals captured in the second sample
m2	Number of recaptures. Either this or the estimated abundance (estN) must be specified.
nsim	Number of simulated values to draw. Defaults to 100000.
alternative	Direction of the alternative hypothesis. Allowed values are "less", "greater", or "2-sided". Defaults to "less".

Value

An approximate p-value for the specified hypothesis test. If m2 is specified rather than estN, output will be returned as a list with two elements: the estimated abundance and p-value.

Note

Any Petersen-type estimator (such as this) depends on a set of assumptions:

• The population is closed; that is, that there are no births, deaths, immigration, or emigration between sampling events

• All individuals have the same probability of capture in one of the two events, or complete mixing occurs between events

• Marking in the first event does not affect probability of recapture in the second event

• Individuals do not lose marks between events

• All marks will be reported in the second event

Author(s)

Matt Tyers

See Also

NChapman, vChapman, seChapman, rChapman, powChapman, ciChapman

Examples

output <- pChapman(nullN=500, n1=100, n2=100, m2=28)
output

plotdiscdensity(rChapman(length=100000, N=500, n1=100, n2=100))
abline(v=output$estN, lwd=2, col=2)
abline(v=500, lwd=2, lty=2)


output <- pChapman(nullN=500, n1=100, n2=100, m2=28, alternative="2-sided")
output

plotdiscdensity(rChapman(length=100000, N=500, n1=100, n2=100))
twosided <- 500 + c(-1,1)*abs(500-output$estN)
abline(v=twosided, lwd=2, col=2)
abline(v=500, lwd=2, lty=2)

mbtyers/recapr documentation built on Sept. 13, 2021, 11:54 a.m.