Distance

The Distance project provides software for designing and analysing distance sampling surveys of wildlife populations. This software takes two forms: a Windows-based program and a suite of packages for the statistical programming language R. It has been produced and developed by a St Andrews team, including Professor Steve Buckland, Professor David Borchers and Professor Len Thomas, for over 20 years.

Distance sampling is a widely used methodology for estimating animal density or abundance. Its name derives from the fact that the information used for inference is the recorded distances to objects of interest (usually animals) obtained by surveying lines or points. In the case of lines, the perpendicular distances to detected animals are recorded, while in the case of points, the radial distances from the point to detected animals are recorded. A key underlying concept is that the probability of detecting an animal decreases as its distance from the observer increases. Much of distance sampling methodology is concentrated on detection functions which model the probability of detecting an animal, given its distance from the transect.

The Distance website provides an introductory free online course, and details of workshops, normally in St Andrews, for more advanced training.