Rcapture (version 1.1)

descriptive: Descriptive Statistics

Description

This function produces descriptive statistics for capture-recapture data.

Usage

descriptive(X, dfreq=FALSE)

## S3 method for class 'descriptive':
print(x, \dots)

## S3 method for class 'descriptive':
plot(x, \dots)

Arguments

X

The table of the observed capture histories in one of the two accepted formats. In the default format, it has one row per unit captured in the experiment. In this case, the number of columns in the table represents the number of capture occasions in the e

dfreq

This argument specifies the format of the data matrix X. By default, it is set to FALSE, which means that X has one row per unit. If it is set to TRUE, then the matrix X contains frequencies in its last column.

x

An object, produced by the descriptive function, to print or to plot.

...

Further arguments passed to or from other methods.

Value

• n
  The total number of captured units.
• base.freq
  A table of basic descriptive statistics. For $i=1,\ldots,t$ : fi{the number of units captured $i$ times} ui{the number of units captured for the first time on occasion $i$ } vi{the number of units captured for the last time on occasion $i$ } ni{the number of units captured on occasion $i$ }.
• m.array
  A $t$ by $t$ matrix containing recapture statistics for units released on occasion $i$, for $i=1,\ldots,t$ : ni{the number of units captured on occasion $i$ } c2{the number of units caught on occasion $i$ recaptured for the first time on occasion 2} .... ct{the number of units caught on occasion $i$ recaptured for the first time on occasion $t$ } not recapt{the number of units caught on occasion $i$ never recaptured}.

Details

The plot.descriptive function produces exploratory heterogeneity graphs. In absence of heterogeneity, the relations presented in the two graphs should be almost linear. Convex fonctions indicate heterogeneity.

References

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/ Lindsay, B. G. (1986) Exponential family mixture models (with least-squares estimators). Annals of Statistics, 14, 124-137. Rivest, L.P. (2008). Why a time effect often has a limited impact on capture-recapture estimates in closed populations. Canadian Journal of Statistics, 36(1), to be published.

Examples

data(hare)
desc<-descriptive(hare)
desc
plot(desc)