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You searched for +publisher:"University of Cape Town" +contributor:("Borchers, David"). One record found.

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University of Cape Town

1. Distiller, Greg. A continuous-time formulation for spatial capture-recapture models.

Degree: Image, Statistical Sciences, 2016, University of Cape Town

Spatial capture-recapture (SCR) models are relatively new but have become the standard approach used to estimate animal density from capture-recapture data. It has in the past been impractical to obtain sufficient data for analysis on species that are very difficult to capture such as elusive carnivores that occur at low density and range very widely. Advances in technology have led to alternative ways to virtually "capture" individuals without having to physically hold them. Some examples of these new non-invasive sampling methods include scat or hair collection for genetic analysis, acoustic detection and camera trapping. In traditional capture-recapture (CR) and SCR studies populations are sampled at discrete points in time leading to clear and well defined occasions whereas the new detector types mentioned above sample populations continuously in time. Re- searchers with data collected continuously currently need to define an appropriate occasion and aggregate their data accordingly thereby imposing an artificial construct on their data for analytical convenience. This research develops a continuous-time (CT) framework for SCR models by treating detections as a temporal non homogeneous Poisson process (NHPP) and replacing the usual SCR detection function with a continuous detection hazard func- tion. The general CT likelihood is first developed for data from passive (also called "proximity") detectors like camera traps that do not physically hold individuals. The likelihood is then modified to produce a likelihood for single-catch traps (traps that are taken out of action by capturing an animal) that has proven difficult to develop with a discrete-occasion approach. The lack of a suitable single-catch trap likelihood has led to researchers using a discrete-time (DT) multi-catch trap estimator to analyse single-catch trap data. Previous work has found the DT multi-catch estimator to be robust despite the fact that it is known to be based on the wrong model for single-catch traps (it assumes that the traps continue operating after catching an individual). Simulation studies in this work confirm that the multi-catch estimator is robust for estimating density when density is constant or does not vary much in space. However, there are scenarios with non-constant density surfaces when the multi-catch estimator is not able to correctly identify regions of high density. Furthermore, the multi-catch estimator is known to be negatively biased for the intercept parameter of SCR detection functions and there may be interest in the detection function in its own right. On the other hand the CT single-catch estimator is unbiased or nearly so for all parameters of interest including those in the detection function and those in the model for density. When one assumes that the detection hazard is constant through time there is no impact of ignoring capture times and using only the detection frequencies. This is of course a special case and in reality detection hazards will tend to vary in time. However when one assumes that the… Advisors/Committee Members: Borchers, David (advisor), Erni, Birgit (advisor).

Subjects/Keywords: Statistical Sciences

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Distiller, G. (2016). A continuous-time formulation for spatial capture-recapture models. (Thesis). University of Cape Town. Retrieved from http://hdl.handle.net/11427/22791

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Distiller, Greg. “A continuous-time formulation for spatial capture-recapture models.” 2016. Thesis, University of Cape Town. Accessed November 23, 2020. http://hdl.handle.net/11427/22791.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Distiller, Greg. “A continuous-time formulation for spatial capture-recapture models.” 2016. Web. 23 Nov 2020.

Vancouver:

Distiller G. A continuous-time formulation for spatial capture-recapture models. [Internet] [Thesis]. University of Cape Town; 2016. [cited 2020 Nov 23]. Available from: http://hdl.handle.net/11427/22791.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Distiller G. A continuous-time formulation for spatial capture-recapture models. [Thesis]. University of Cape Town; 2016. Available from: http://hdl.handle.net/11427/22791

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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