periodhist {Rcapture} | R Documentation |
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.
periodhist(X, dfreq=FALSE, vt, drop=TRUE)
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, meanning that in the output matrix the unobserved capture histories having a frequency of 0 are omitted. To keep them, drop must be set to FALSE. |
This function is useful when using an open population model to analyse a robust design data set. It can be used to reduce the data set to one observation per primary period. The observation is one for a unit caught at least once during the period and zero for 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 in argument to an model fiting function, the dfreq
argument must be set to TRUE.
A 2^I-1 by I+1 matrix of all the pooled capture histories, with their observed frequencies.
Sophie Baillargeon Sophie.Baillargeon@mat.ulaval.ca and
Louis-Paul Rivest Louis-Paul.Rivest@mat.ulaval.ca
Baillargeon, S. and Rivest, L.P. (2007) Rcapture: Loglinear models for capture-recapture in R. Journal of Statistical Software, 19(5), http://www.jstatsoft.org/v19/i05.
data(mvole) mvole.op<-periodhist(mvole,vt=rep(5,6)) openp(mvole.op, dfreq=TRUE)