PetersenEst: Calculate Petersen Abundance Estimates.

In jasondubois/sportfish: Methods and Function for CDFW Sportfish Unit Data

Description

PetersenEst calculates abundance estimates using mark-recapture data. Function is designed following equations detailed in Ricker 1975 (see References). Currently, we use Bailey's modified equation (see eqn 3.9, page 79 in Ricker 1975).

Usage

PetersenEst(x, ...)

## S3 method for class 'numeric'
PetersenEst(x, CC, RR, ..., alpha = 0.05)

## S3 method for class 'PetersenEst'
print(x, ...)

Arguments

x	Numeric. Number of fish marked (tagged).
...	Currently not used.
CC	Numeric. Number of fish caught or sampled.
RR	Numeric. Number of recaptured fish (tags) in the sample.
alpha	Numeric scalar used to calculated z-value for defining confidence intervals (e.g., 95%). Default at 0.05 (or 95%).

Value

A list (of class PetersenEst) containing items in Values section.

Methods (by class)

• numeric: for object class 'numeric'.

• PetersenEst: print method (See notes).

Values

N

absolute abundance estimate

.

Var

variance of N

.

CI

confidence interval as SE * Z

.

SE

standard error as sqrt(Var)

.

Level

CI level as a result of Z; e.g., 95%

.

Z

given as qnorm(1 - alpha / 2), where alpha = 0.05 for 95% CI

.

Note

Method print written for class PetersenEst returns estimate with confidence interval.

References

Ricker, W.E. (1975). Computation and interpretation of biological statistics of fish populations. Bulletin of the Fisheries Research Board of Canada, Bulletin 191, Ottawa. http://www.dfo-mpo.gc.ca/Library/1485.pdf

Examples

# coming soon

jasondubois/sportfish documentation built on July 3, 2020, 1:01 p.m.