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Accuracy and precision of dolphin group size estimates

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Accuracy and precision of dolphin group size estimates. / Gerrodette, Tim; Perryman, Wayne L.; Oedekoven, Cornelia S.

In: Marine Mammal Science, Vol. 35, No. 1, 01.2019, p. 22-39.

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Gerrodette, T, Perryman, WL & Oedekoven, CS 2019, 'Accuracy and precision of dolphin group size estimates' Marine Mammal Science, vol. 35, no. 1, pp. 22-39. https://doi.org/10.1111/mms.12506

APA

Gerrodette, T., Perryman, W. L., & Oedekoven, C. S. (2019). Accuracy and precision of dolphin group size estimates. Marine Mammal Science, 35(1), 22-39. https://doi.org/10.1111/mms.12506

Vancouver

Gerrodette T, Perryman WL, Oedekoven CS. Accuracy and precision of dolphin group size estimates. Marine Mammal Science. 2019 Jan;35(1):22-39. https://doi.org/10.1111/mms.12506

Author

Gerrodette, Tim ; Perryman, Wayne L. ; Oedekoven, Cornelia S. / Accuracy and precision of dolphin group size estimates. In: Marine Mammal Science. 2019 ; Vol. 35, No. 1. pp. 22-39.

Bibtex - Download

@article{4f79c0a9dba74618a896a63083795eb3,
title = "Accuracy and precision of dolphin group size estimates",
abstract = "Estimating the number of dolphins in a group is a challenging task. To assess the accuracy and precision of dolphin group size estimates, observer estimates were compared to counts from large‐format vertical aerial photographs. During 11 research cruises, a total of 2,435 size estimates of 434 groups were made by 59 observers. Observer estimates were modeled as a function of the photo count in a hierarchical Bayesian framework. Accuracy varied widely among observers, and somewhat less widely among dolphin species. Most observers tended to underestimate, and the tendency increased with group size. Groups of 25, 50, 100, and 500 were underestimated by <1{\%}, 16{\%}, 27{\%}, and 47{\%}, respectively, on average. Precision of group size estimates was low, and estimates were highly variable among observers for the same group. Predicted true group size, given an observer estimate, was larger than the observer estimate for groups of more than about 25 dolphins. Predicted group size had low precision, with coefficients of variation ranging from 0.7 to 1.9. Studies which depend on group size estimates will be improved if the tendency to underestimate group size and the high uncertainty of group size estimates are included in the analysis.",
keywords = "Group size estimation, Abundance estimation, Aerial photography, Bayesian hierarchical model, Random-effects model, Reversible jump MCMC",
author = "Tim Gerrodette and Perryman, {Wayne L.} and Oedekoven, {Cornelia S.}",
year = "2019",
month = "1",
doi = "10.1111/mms.12506",
language = "English",
volume = "35",
pages = "22--39",
journal = "Marine Mammal Science",
issn = "0824-0469",
publisher = "John Wiley & Sons, Ltd (10.1111)",
number = "1",

}

RIS (suitable for import to EndNote) - Download

TY - JOUR

T1 - Accuracy and precision of dolphin group size estimates

AU - Gerrodette, Tim

AU - Perryman, Wayne L.

AU - Oedekoven, Cornelia S.

PY - 2019/1

Y1 - 2019/1

N2 - Estimating the number of dolphins in a group is a challenging task. To assess the accuracy and precision of dolphin group size estimates, observer estimates were compared to counts from large‐format vertical aerial photographs. During 11 research cruises, a total of 2,435 size estimates of 434 groups were made by 59 observers. Observer estimates were modeled as a function of the photo count in a hierarchical Bayesian framework. Accuracy varied widely among observers, and somewhat less widely among dolphin species. Most observers tended to underestimate, and the tendency increased with group size. Groups of 25, 50, 100, and 500 were underestimated by <1%, 16%, 27%, and 47%, respectively, on average. Precision of group size estimates was low, and estimates were highly variable among observers for the same group. Predicted true group size, given an observer estimate, was larger than the observer estimate for groups of more than about 25 dolphins. Predicted group size had low precision, with coefficients of variation ranging from 0.7 to 1.9. Studies which depend on group size estimates will be improved if the tendency to underestimate group size and the high uncertainty of group size estimates are included in the analysis.

AB - Estimating the number of dolphins in a group is a challenging task. To assess the accuracy and precision of dolphin group size estimates, observer estimates were compared to counts from large‐format vertical aerial photographs. During 11 research cruises, a total of 2,435 size estimates of 434 groups were made by 59 observers. Observer estimates were modeled as a function of the photo count in a hierarchical Bayesian framework. Accuracy varied widely among observers, and somewhat less widely among dolphin species. Most observers tended to underestimate, and the tendency increased with group size. Groups of 25, 50, 100, and 500 were underestimated by <1%, 16%, 27%, and 47%, respectively, on average. Precision of group size estimates was low, and estimates were highly variable among observers for the same group. Predicted true group size, given an observer estimate, was larger than the observer estimate for groups of more than about 25 dolphins. Predicted group size had low precision, with coefficients of variation ranging from 0.7 to 1.9. Studies which depend on group size estimates will be improved if the tendency to underestimate group size and the high uncertainty of group size estimates are included in the analysis.

KW - Group size estimation

KW - Abundance estimation

KW - Aerial photography

KW - Bayesian hierarchical model

KW - Random-effects model

KW - Reversible jump MCMC

U2 - 10.1111/mms.12506

DO - 10.1111/mms.12506

M3 - Article

VL - 35

SP - 22

EP - 39

JO - Marine Mammal Science

T2 - Marine Mammal Science

JF - Marine Mammal Science

SN - 0824-0469

IS - 1

ER -

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ID: 253087923