logObsInd: The actual observation index function

In BIRDS: Biodiversity Information Review and Decision Support

Description

This function implements the algorithms to calculate the observation index. OI = log ( (At / (At + Rt) ) / ( A / (A + R) ) ) where At is the sum of observations for focal species during time t (or grid), Rt is sum of observations of all species in reference group during t, A and R are the total sums for observations.

Usage

logObsInd(focal, group, fs.rm = TRUE, norm = TRUE)

Arguments

focal	observations/visits for the focal species
group	observations/visits for the reference species group
fs.rm	if TRUE, assumes that the observations for the focal species are included in 'group' and will remove them
norm	if TRUE, the result is normalized to a 0-1 range

Value

a positive observation index

References

Telfer, Preston & Rothery (2002) <doi:10.1016/S0006-3207(02)00050-2>

BIRDS documentation built on June 27, 2021, 1:06 a.m.