Results 251 to 260 of about 4,209,032 (298)

Line Transect Sampling in Small and Large Regions

Biometrics, 2005
SummaryMelville and Welsh(2001,Biometrics57,1130–1137) consider an approach to line transect sampling using a separate calibration study to estimate the detection functiong. They present a simulation study contrasting their results with poor results from a traditional estimator, labeled the “Buckland” estimator and referenced toBuckland et al.(1993 ...
Rachel Fewster, Stephen Buckland, Jeffrey L Laake   +2 more
exaly   +3 more sources

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

A Semiparametric Model for Line Transect Sampling

Communications in Statistics - Theory and Methods, 2006
This paper introduces an appealing semiparametric model for estimating wildlife abundance based on line transect data. The proposed method requires the existence of a parametric model and then improves the estimator using a kernel method. Properties of the resultant estimator are derived and an expression for the asymptotic mean square error (AMSE) of ...
exaly   +2 more sources

On the Line Transect Sampling Method

Biometrics, 1974
Theory has been developed in the present paper for estimating wildlife density and its standard error by the line transect method of sampling using both right angle and radial distances and based on different assumptions than those made by Gates et al. [1968]. It is shown that relatively better fits are realized when the assumptions are tested with the
Sen, A. R., Tourigny, J., Smith, G. E. J.   +2 more
openaire   +1 more source

Comparison of Helicopter Line Transects with Walked Line Transects for Estimating Densities of Kangaroos

Wildlife Research, 1997
The performance of helicopter surveys for estimating population densities of red kangaroos ( Macropus rufus ), eastern grey kangaroos ( Macropus giganteus ) and common wallaroos ( Macropus robustus ) was investigated by comparing line-transect density estimates obtained from helicopter surveys with those from ground (walked) surveys.
Clancy, T. F., Pople, A. R., Gibson, L. A.   +2 more
openaire   +3 more sources

Sequential Estimation in Line Transect Surveys

Biometrics, 2002
This article considers using sequential procedures to determine the amount of survey effort required in a line transect survey in order to achieve a certain precision level in estimating the abundance of a biological population. Sequential procedures are constructed for both parametric and nonparametric animal abundance estimators.
Yip, PSF, Zhou, Y, Chen, SX
openaire   +5 more sources

Line transects

2001
Abstract The purpose of this chapter is to illustrate the application of the theory of Chapter 3 to line transect data, and to present the strategies for analysis outlined in Section 2.5. In general, the parameter f (0) in a line transect analysis does not have a closed form estimator. That is, for most models f(0) cannot be expressed as
S T Buckland, D R Anderson, K P Burnham, J L Laake, D L Borchers, L Thomas   +5 more
openaire   +1 more source

Size Bias in Line Transect Sampling

Biometrics, 1987
Line transect sampling is used to estimate the number of individuals in a study area. It is usually assumed that the detections of individuals constitute independent events, and that the probability of detecting an item is a function of its perpendicular distance from the transect.
Drummer, Thomas D., McDonald, Lyman L.
openaire   +2 more sources

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.
openaire   +2 more sources

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