Basic Concepts of Line-Transect Sampling 1. Not all individuals will be detected The probability of detecting an object decreases as its distance from the line increases. The Fourier series estimator is the most robust estimation model but it only works with perpendicular-distance data. However, a Windows version is coming out that will be more user-friendly and should be available by January, 1999. Distance and angles are measured exactly.
Sightings are independent events.
Proper estimation of density via line transect sampling schemes involves a mix of basic statistical-sampling theory and biological knowledge of the population under study. The observer must be able to determine the position of the line at all times. In some cases, a series of straight line segments will suffice. Care must be taken to assure that objects on the center line of the transect are seen with probability equal to one. In practice, this often can be met if the observer walks carefully along the center of the line transect at all times.