abundance | R Documentation |
The function abundance
applies the methodology found in Rivest et al. (1998) for estimating
caribou abundance using postcalving aggregations detected by radio telemetry.
abundance(mat, n, model = c("H", "I", "T"), B, maxT.hat) ## S3 method for class 'abundance' print(x,...)
mat |
A matrix containing in the first column the number of radio-collared animals in the detected (photographed) groups and in the second column the corresponding size of the detected groups. |
n |
A numeric: the total number of active collars during the census. |
model |
A character string indicating the model to determine the probability that a group with collared animals is detected pi. It can be either "H" = homogeneity model, "I" = independence model or "T" = threshold model (see Details). The default is "H". |
B |
A numeric: a bound for the threshold model. |
maxT.hat |
A numeric: an upper bound used in the numerical computation of |
x |
An object, produced by the |
... |
Further arguments to be passed to methods (see |
DETECTION MODELS
- homogeneity model (model="H"
):
pi = r if xi>=1
- independence model (model="I"
):
pi = 1-(r^xi)
- threshold model (model="T"
):
pi = 1 if xi>=B, r if 1<=xi<B
where pi is the probability that a group with collared animals is detected,
xi is the number of radio-collared in the detected (photographed) groups and
r is a parameter related to the probability of detection.
For the threshold model, B
is a bound given as a function's argument.
mp |
The number of detected groups having radio-collared animals. |
xt |
The total number of radio-collared animals found in the detected groups. |
gnt |
The total number of animals counted in the detected groups. |
rr |
The estimated parameter related to the probability of detection. |
se_rr |
The estimated standard error of |
mat_pi |
A matrix containing a sorted copy of the input matrix |
T.hat |
The estimator for the total number of animals in a herd. |
se_T.hat |
The estimated standard error of |
loglikelihood |
The maximum value of the loglikelihood function for the detected model. |
randomness_test |
A vector with the statistic and the p-value of a score test for the randomness assumption available only for the homogeneity, independence and threshold model with B=2 or 3. |
call |
The function call (object of class "call"). |
Louis-Paul Rivest Louis-Paul.Rivest@mat.ulaval.ca and
Helene Crepeau Helene.Crepeau@mat.ulaval.ca and
Serge Couturier tuttu@videotron.ca and
Sophie Baillargeon Sophie.Baillargeon@mat.ulaval.ca
Rivest, L.-P., Couturier, S. and Crepeau, H. (1998). Statistical Methods for estimating caribou abundance using postcalving aggregations detected by radio telemetry. Biometrics, 54(3), 865-876.
petersen
data(GRH93) abundance(GRH93, n=92) # default model="H" abundance(GRH93, n=92, model="H") abundance(GRH93, n=92, model="I") abundance(GRH93, n=92, model="T", B=2) abundance(GRH93, n=92, model="T", B=4) abundance(GRH93, n=92, model="T", B=6)
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