periodhist: Merge capture occasions

In Rcapture: Loglinear Models for Capture-Recapture Experiments

Merge capture occasions

Description

This function produces a reduced matrix of capture histories from a complete one by merging together some capture occasions.

It can also be used to change the format of a capture-recapture data set with complete capture histories: it transforms a data set with one row per captured unit to a data set with one row per capture history followed by its frequency.

Usage

periodhist(X, dfreq=FALSE, vt, drop=TRUE)

Arguments

X	The matrix of the observed capture histories (see Rcapture-package for a description of the accepted formats).
dfreq	A logical. By default FALSE, which means that X has one row per unit. If TRUE, it indicates that the matrix X contains frequencies in its last column.
vt	A vector containing the numbers of capture occasions for each pooled capture occasions. The length of this vector equals the number of capture occasions in the reduced matrix (noted I).
drop	A logical, by default TRUE, meaning that in the output matrix the unobserved capture histories (frequency of 0) are omitted. To keep them, drop must be set to FALSE.

Details

This function is useful when using an open population model to analyze a robust design data set. It can be used to reduce the data set to one observation per primary period. A one represents a unit caught at least once during the period and a zero a unit never caught.

It is also useful for experiments with a large number of capture occasions but a limited number of catches, especially when there is no capture on some occasions. In such cases, one can pool together some capture occasions with the periodhist function.

If a data matrix produced by the periodhist function is given as an argument to a Rcapture function, the dfreq argument must be set to TRUE.

Value

A 2^I-1 by I+1 matrix of all the pooled capture histories, with their observed frequencies. If drop=TRUE (the default), the number of rows of this matrix is in fact 2^I-1 minus the number of unobserved capture histories.

Author(s)

Louis-Paul Rivest [e-mail] and Sophie Baillargeon

References

Baillargeon, S. and Rivest, L.P. (2007) Rcapture: Loglinear models for capture-recapture in R. Journal of Statistical Software, 19(5), doi: 10.18637/jss.v019.i05.

See Also

openp

Examples

# mvole data set aggregated per primary period
mvole.op <- periodhist(mvole, vt = rep(5, 6))
openp(mvole.op, dfreq = TRUE)

Rcapture documentation built on May 4, 2022, 5:05 p.m.