create.NHAT: Estimated number of individuals for each detection

In lindesaysh/MRSea: Spatially adaptive regression splines using SALSA

Estimated number of individuals for each detection

Description

This function creates a new column in data which contains the estimated number of animals for each detection. This is the number of observed individuals divided by their probability of detection using MCDS methods (size/detection probability). In the case that no size column is given in dis.data, it is assumed that detections were made of individuals and size is set to 1 for all detections. The values for size and NHAT are set to zero in case the distance was larger than the truncation distance w specified in det.fct.object. In addition, a new column area is created which is used as the offset in the second stage count model (segment length * (truncation distance/1000) * 2). The truncation distance is divided by 1000 to convert it from metres to km. It is assumed that the segment data represents two-sided surveys. In case the survey was one-sided, this column needs to be divided by 2 after the call to this function.

Usage

create.NHAT(data, ddf.obj)

Arguments

data	distance data object used with det.fct to estimate probabilities of detection
ddf.obj	detection function object created by ddf

Examples

data(dis.data.re)
result<-ddf(dsmodel=~mcds(key="hn", formula=~1), data=dis.data.re,method="ds", 
     meta.data= list(width=250,binned=FALSE))
dis.data<-create.NHAT(dis.data.re,result)

lindesaysh/MRSea documentation built on May 11, 2024, 11:30 p.m.