distance.sample.size (version 0.0)

calculate.theta.given.mean.detection.prob: Function for internal use only.

Description

Calculates the value of the first element of the detection parameters theta based on a supplied value of the average detection rate. Primarily for internal use.

Usage

calculate.theta.given.mean.detection.prob(detection.function, theta2, w, mean.detection.prob.value, stop = F)

Arguments

detection.function

The detection function. Only "halfnormal" and "hazard" (hazard rate) are supported at present.

theta2

The second detection parameter for the hazard rate model (the shape parameter). Not required for halfnormal.

w

The maximum range of observation. Objects at distance greater than w from the observer are assumed to never be recorded.

mean.detection.prob.value

The mean detection probability over the range of observation.

stop

Set to T to open a browser window (for debugging purposes)

Value

The value of the first parameter of theta.

References

Buckland S, Anderson D, Burnham K, Laake J and Borchers D (2001). Introduction to Distance Sampling: Estimating Abundance of Biological Populations. Oxford: Oxford University Press.

Clark, R. G. (2016), "Statistical efficiency in distance sampling," PLoS One, forthcoming, www.plosone.org

Examples

calculate.theta.given.mean.detection.prob(detection.function="hazard",theta2=2,w=1,
mean.detection.prob.value=0.6) # should equal 0.448
calculate.theta.given.mean.detection.prob(detection.function="halfnormal",w=1,
mean.detection.prob.value=0.6) # should equal 0.502