Extract or replace usage (effort) information of a
numeric matrix of detectors x occasions
other arguments (not used)
In secr versions before 2.5.0, usage was defined as a binary value (1 if trap k used on occasion s, zero otherwise).
In later versions, usage may take nonnegative real values and will be interpreted as effort. This corresponds to the constant T_s used for the duration of sampling by Borchers and Efford (2008). Effort is modelled as a known linear coefficient of detection probability on the hazard scale (secr-varyingeffort.pdf; Efford et al. 2013).
For replacement of usage, various forms are possible for
- a matrix in which the number of rows of
matches the number of traps K in
- a vector of two values, the usage (typically 1) and the number of occasions S (a K x S matrix will be filled with the first value)
- a vector of R+1 values where R is the number of sessions in a multi-session object and elements 2..R+1 correspond to the numbers of occasions S1, S2,... in each session
- the usage only (typically 1) (only works when replacing an existing usage matrix with known number of occasions).
usage(object) returns the usage matrix of the
usage(object) may be NULL.
At present, assignment of usage to the traps objects of a multisession capthist object results in the loss of session names from the latter.
Efford, M. G., Borchers D. L. and Mowat, G. (2013) Varying effort in capture–recapture studies. Methods in Ecology and Evolution 4, 629–636.
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