ip2: Four-parameter inverse power hazard detection function

In david-borchers/LT2D: Line transect estimation in two dimensions

Description

Inverse power hazard function, as per Borchers and Langrock (in press): Has form h(y,x)=theta[1]*(1/(1+(x/theta[2])^2+(y/theta[4])^2))^(theta[3]+1).

Usage

ip2(y, x, b)

Arguments

y	Forward distance
x	perpendicular distance
b	parameter vector, where b[1] is plogis(theta[1]) b[2] is log(theta[2]), where theta[2] is the scale parameter for x, b[3] is log(theta[3]) and b[2] is log(theta[4]), where theta[4] is the scale parameter for y.

Value

probability of detection given that an animal is availabe at location x,y #'@examples b=c(-23.725809,-3.136638,2.122910,-3.136638) ip2(0.5,0.5,b=b) yy=seq(0,0.03,length=100);xx=rep(0,100) hh=ip2(yy,xx,b=b) plot(yy,hh,type="l")

References

Borchers, D.L and Langrock, R."Double-observer line transect surveys with Markov- modulated Poisson process models for animal availability" Biometrics (in press).

david-borchers/LT2D documentation built on Aug. 17, 2020, 1:37 a.m.