Results 211 to 220 of about 16,314 (251)

On a Basic Assumption in the Line Transect Method

Biometrical Journal, 1978
AbstractThis paper deals with one of the basic assumptions made in estimating population density by the line transect sampling method. Theory has been developed in this paper for estimating, density using a gamma distribution. The results have been applied to data on ruffed grouse.
Sen, A. R., Smith, G. E. J., Butler, G.
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Line Transect Estimators for Left-Truncated Distributions

Biometrics, 1985
Left-truncated line transect data sets may occur when surveying with certain types of aircraft where the observer cannot look straight down. A general model of left-truncation in line transect sampling is developed and parametric estimators are derived in such cases when the underlying distribution of right-angle distances is either exponentially or ...
Alldredge, J. Richard, Gates, Charles E.
openaire   +3 more sources

Comment on Cowling's “Spatial Methods for Line Transect Surveys”

Biometrics, 2003
Summary. We consider the problem of estimating the parameters of a two‐dimensional Neyman‐Scott process, from data collected through a line transect survey.Cowling(1998,Biometrics54,828–839) suggested an estimation method based on a one‐dimensional K‐function along the transect line. However, her expression for the theoretical K‐function is wrong.
Marit Holden, Magne Aldrin, Tore Schweder   +2 more
exaly   +4 more sources

A Robust Line Transect Method

Biometrics, 1992
SUMMARY Standard line transect estimation is not robust to departures from the assumptions that animals do not move in response to the observer before detection and that all animals on or near the trackline are detected. We propose field methodology and analysis methods for which estimates are robust to the first assumption and do not require the ...
Stephen T. Buckland, Benjamin J. Turnock
openaire   +1 more source

Hazard Models for Line Transect Surveys with Independent Observers

Biometrics, 1999
Summary. The likelihood function for data from independent observer line transect surveys is derived, and a hazard model is proposed for the situation where animals are available for detection only at discrete time points. Under the assumption that the time points of availability follow a Poisson point process, we obtain an analytical expression for ...
Hans J Skaug
exaly   +3 more sources

Measurement Errors in Line Transect Surveys

Biometrics, 1998
Summary: An important assumption used in the analysis of line transect data for animal abundance estimation is that the perpendicular sighting distances of detected animals to transect lines are measured accurately. However, in many line transect surveys, the sighting distances are likely to be subject to measurement errors.
openaire   +1 more source

Line Transect Sampling from a Curving Path

Biometrics, 2001
Cutting straight line transects through dense forest is time consuming and expensive when large areas need to be surveyed for rare or highly clustered species. We argue that existing paths or game trails may be suitable as transects for line transect sampling even though they will not, in general, run straight.
L, Hiby, M B, Krishna
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Parametric Models for Line Transect Surveys

Biometrika, 1979
SUMMARY With data from line transect surveys, the pattern of distances at which animals are detected provides the information for estimating the area which the observer effectively surveys. This paper suggests a parametric structure for the problem wherein this area is characterized by an effective half-width parameter which appears as a scale ...
openaire   +2 more sources

Mark-Recapture Models for Line Transect Surveys

Biometrics, 1998
Summary: One of the key assumptions of conventional line transect (LT) theory is that all animals in the observer's path are detected. When this assumption fails, simultaneous survey by two independent observers can be used to estimate detection probabilities and abundance.
Borchers, David L., Zucchini, Walter, Fewster, Rachel M.   +2 more
openaire   +1 more source

Spatial Methods for Line Transect Surveys

Biometrics, 1998
Summary: Line transect surveys have traditionally been used only to estimate the mean intensity of an underlying spatial point process. We propose a test for complete spatial randomness and a method of estimating the clustering parameters in a simplified Neyman-Scott Poisson model, using observations collected in a line transect survey with a Gaussian ...
openaire   +2 more sources