Geoscience Reference
In-Depth Information
use the full facilities of the program Distance, a 362-page user's manual that
comes with the program should be read.
Calculations of different parameter estimates in line and point transect
sampling can also be performed in three recently published R packages:
unmarked (Fiske and Chandler, 2011), Rdistance (McDonald, 2012), and
mrds (Laake et al
.,
2013). Unmarked is an R package that fits a variety of
hierarchical models to data collected using survey methods such as point
counts, site occupancy sampling, line transect sampling, removal sampling,
and double-observer sampling. For the most part, this package performs a
subset of the analyses available in the Distance program. Rdistance is able to
run all the procedures indicated in Distance as classic distance sampling, but
it also includes routines to it a gamma distance function, and the uniform
distance function of Rdistance is parameterized differently. The mrds pack-
age analyzes single- or double-observer distance-sampling data for line or
point sampling. A simpler interface of mrds, called Distance (homonym of
the stand-alone program; Miller 2013), has also been created in R to facilitate
the estimation process of the detection function and the abundance/density
of objects in line and point transect sampling.
