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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University of Cape Town
1983
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ftunivcapetownir:oai:localhost:11427/16843 2023-05-15T17:12:50+02:00 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 1983 application/pdf http://hdl.handle.net/11427/16843 https://open.uct.ac.za/bitstream/11427/16843/1/thesis_sci_1983_basson_marinelle.pdf eng eng University of Cape Town Faculty of Science Department of Mathematics and Applied Mathematics http://hdl.handle.net/11427/16843 https://open.uct.ac.za/bitstream/11427/16843/1/thesis_sci_1983_basson_marinelle.pdf Mathematical Statistics Operations Research Master Thesis Masters MSc 1983 ftunivcapetownir 2022-09-13T05:47:32Z 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. Master Thesis minke whale University of Cape Town: OpenUCT |
institution |
Open Polar |
collection |
University of Cape Town: OpenUCT |
op_collection_id |
ftunivcapetownir |
language |
English |
topic |
Mathematical Statistics Operations Research |
spellingShingle |
Mathematical Statistics Operations Research Basson, Marinelle A simulation study of the effect of target motion on sighting estimates of minke whale population density |
topic_facet |
Mathematical Statistics Operations Research |
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. |
author2 |
Butterworth, Doug S Underhill, Leslie G |
format |
Master Thesis |
author |
Basson, Marinelle |
author_facet |
Basson, Marinelle |
author_sort |
Basson, Marinelle |
title |
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_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_sort |
simulation study of the effect of target motion on sighting estimates of minke whale population density |
publisher |
University of Cape Town |
publishDate |
1983 |
url |
http://hdl.handle.net/11427/16843 https://open.uct.ac.za/bitstream/11427/16843/1/thesis_sci_1983_basson_marinelle.pdf |
genre |
minke whale |
genre_facet |
minke whale |
op_relation |
http://hdl.handle.net/11427/16843 https://open.uct.ac.za/bitstream/11427/16843/1/thesis_sci_1983_basson_marinelle.pdf |
_version_ |
1766069712568975360 |