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A simulation study of the effect of target motion on sighting estimates of minke whale population density
Line transect methods used to estimate population density assume stationarity of targets. Violation of this assumption leads to overestimation of the true density. A simulation study based on a hazard-rate model is used to assess the resulting bias. The model is calibrated to generate sighting data...
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| Format: | Thesis |
| Language: | English |
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Department of Mathematics and Applied Mathematics
2016
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| _version_ | 1867613177034833920 |
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| access_status_str | Open Access |
| author | Basson, Marinelle |
| author2 | Butterworth, Doug S |
| author_browse | Basson, Marinelle Butterworth, Doug S |
| author_facet | Butterworth, Doug S Basson, Marinelle |
| author_sort | Basson, Marinelle |
| collection | Thesis |
| description | Line transect methods used to estimate population density assume stationarity of targets. Violation of this assumption leads to overestimation of the true density. A simulation study based on a hazard-rate model is used to assess the resulting bias. The model is calibrated to generate sighting data resembling real data from minke whale sighting surveys. The procedure currently used to calculate a corrected negative exponential density estimate from sighting data is duplicated using simulated data. The resulting estimates are compared to the true population density determined by the simulation. Results reveal that in the case considered, the method of calculating the g(O) factor (which corrects for the fact that all animals on the trackline are not sighted) leads to a greater degree of overestimation than the effect of target motion at 3 knots. Shortcomings of the model are pointed out and possible improvements suggested. It is also suggested that further research be focused initially on the calculation of the g(O) correction factor rather than on effects of target motion. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/16843 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:31:58.458Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2016 |
| publishDateRange | 2016 |
| publishDateSort | 2016 |
| publisher | Department of Mathematics and Applied Mathematics |
| publisherStr | Department of Mathematics and Applied Mathematics |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/16843 A simulation study of the effect of target motion on sighting estimates of minke whale population density Basson, Marinelle Butterworth, Doug S Underhill, Leslie G Mathematical Statistics Operations Research Line transect methods used to estimate population density assume stationarity of targets. Violation of this assumption leads to overestimation of the true density. A simulation study based on a hazard-rate model is used to assess the resulting bias. The model is calibrated to generate sighting data resembling real data from minke whale sighting surveys. The procedure currently used to calculate a corrected negative exponential density estimate from sighting data is duplicated using simulated data. The resulting estimates are compared to the true population density determined by the simulation. Results reveal that in the case considered, the method of calculating the g(O) factor (which corrects for the fact that all animals on the trackline are not sighted) leads to a greater degree of overestimation than the effect of target motion at 3 knots. Shortcomings of the model are pointed out and possible improvements suggested. It is also suggested that further research be focused initially on the calculation of the g(O) correction factor rather than on effects of target motion. 2016-02-08T07:08:23Z 2016-02-08T07:08:23Z 1983 Master Thesis Masters MSc http://hdl.handle.net/11427/16843 eng application/pdf Department of Mathematics and Applied Mathematics Faculty of Science University of Cape Town |
| spellingShingle | Mathematical Statistics Operations Research Basson, Marinelle A simulation study of the effect of target motion on sighting estimates of minke whale population density |
| thesis_degree_str | Master's |
| title | A simulation study of the effect of target motion on sighting estimates of minke whale population density |
| title_full | A simulation study of the effect of target motion on sighting estimates of minke whale population density |
| title_fullStr | A simulation study of the effect of target motion on sighting estimates of minke whale population density |
| title_full_unstemmed | A simulation study of the effect of target motion on sighting estimates of minke whale population density |
| title_short | A simulation study of the effect of target motion on sighting estimates of minke whale population density |
| title_sort | simulation study of the effect of target motion on sighting estimates of minke whale population density |
| topic | Mathematical Statistics Operations Research |
| url | http://hdl.handle.net/11427/16843 |
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