Rdistance (version 2.1.3)

EDR: Effective Detection Radius (EDR) for estimated detection functions with point transects

Description

Computes Effective Detection Radius (EDR) for estimated detection functions with point transects. The point-transect equivalent to Effective Strip Width (ESW).

Usage

EDR(obj, newdata)

Arguments

obj

An estimated detection function object. An estimated detection function object has class 'dfunc', and is usually produced by a call to dfuncEstim. The estimated detection function may optionally contain a \(g(0)\) component. If no \(g(0)\) component is found, \(g(0)\) = 1 is assumed.

newdata

A data frame containing new values of the covariates at which EDR's are sought. If NULL or missing and obj contains covariates, the covariates stored in obj are used. See Value section.

Value

If newdata is not missing and not NULL and covariates are present in obj, returned value is a vector with length equal to the number of rows in newdata. If newdata is missing or NULL and covariates are present in obj, returned value is a vector with length equal to the number of detections in obj$dist. In either of the above cases, elements in the returned vector are the effective detection radii for the corresponding set of covariates.

If obj does not contain covariates, newdata is ignored and a scalar equal to the (constant) effective detection radius for all detections is returned.

Details

The point-transect equivalent to Effective Strip Width (ESW).

See Also

dfuncEstim, ESW, effectiveDistance

Examples

# NOT RUN {
# Load example thrasher data (point transect survey type)
data(thrasherDetectionData)

# Fit half-normal detection function
dfunc <- dfuncEstim(formula=dist~1,
                    detectionData=thrasherDetectionData,
                    likelihood="halfnorm", w.hi=175, pointSurvey=TRUE)

# Compute effective detection radius (EDR)
EDR(dfunc)

# EDR only applies to point transect surveys
# ESW is the line transect equivalent
# The effectiveDistance function tests whether the dfunc was
# fit to line or point data, and returns either ESW or EDR accordingly
effectiveDistance(dfunc)
  
# }