Distance-Sampling Analyses for Density and Abundance Estimation
Calculation of Hermite expansion for detection function likelihoods
Compute the integration constant for distance density functions
isUnitless - Test whether object is unitless
Estimate abundance from distance-sampling data
AICc and related fit statistics for detection function objects
Automated classical distance analysis
Coefficients of an estimated detection function
colorize - Add color to result if terminal accepts it
calculation of cosine expansion for detection function likelihoods
Estimate a detection function from distance-sampling data
Estimate a non-parametric smooth detection function from distance-samp...
Effective Detection Radius (EDR) for estimated detection functions wit...
Calculates the effective sampling distance for estimated detection fun...
Abundance point estimates
Line transect Effective Strip Width (ESW)
Compute double observer probability of detection (No external covariat...
F.gx.estim - Estimate g(0) or g(x)
Find the coordinate of the maximum of a distance function
Return the negative log likelihood for a set of distance values
Set starting values and limits for parameters of Rdistance functions
Gamma.like - Gamma distance function
Gamma.start.limits - Start and limit values for Gamma parameters.
Return model frame for dfunc
Half-normal likelihood function for distance analyses
hazrate.like - Hazard rate likelihood
logistic.start.limits - Start and limit values for logistic distance f...
negexp.like - Negative exponential distance function
Compute off-transect distances from sighting distances and angles
plot.dfunc - Plot method for distance (detection) functions
Predict method for dfunc objects
Print abundance estimates
Print a distance function object
Rdistance - Distance Sampling Analyses for Abundance Estimation
Control parameters for Rdistance optimization.
Numeric second derivatives
Calculate simple polynomial expansion for detection function likelihoo...
Smoothed likelihood function for distance analyses
uniform.like - Uniform distance likelihood
uniform.start.limits - Start and limit values for uniform distance fun...
Likelihood parameter names
lines.dfunc - Lines method for distance (detection) functions
logistic.like - Logistic distance function likelihood
Distance-sampling analyses estimate density and abundance of organisms in ecology when detection probability declines with increasing distance from the observers. Distance-sampling is popular in most branches of ecology and especially when organisms are observed from aerial platforms (e.g., airplane or drone), surface vessels (e.g., boat or truck), or along walking transects. Rdistance analyzes data collected on both point and line transects, estimates overall (study area) and site-level (transect or point) density, and allows users to specify regression-like formula (similar to lm or glm) for covariates. A large suite of classical, parametric detection functions are included along with some uncommon parametric functions (e.g., Gamma, negative exponential) and non-parametric smoothed distance functions. Custom (user-defined) detection functions can be implemented (see vignette). Measurement unit integrity is enforced with internal unit conversion when necessary. The help files and vignettes have been vetted by multiple authors and tested in workshop settings.
Useful links