Flexible parametric modeling of survival from age at death data: A mixed linear regression framework |
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Authors: | Etienne Rouby Vincent Ridoux Matthieu Authier |
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Affiliation: | 1. Centre d'études Biologiques de Chizé, UMR 7372, Villiers-en-Bois, France;2. Centre d'études Biologiques de Chizé, UMR 7372, Villiers-en-Bois, France Observatoire PELAGIS, UMS-CNRS 3462, La Rochelle Université, La Rochelle, France;3. Observatoire PELAGIS, UMS-CNRS 3462, La Rochelle Université, La Rochelle, France ADERA, La Rochelle Université, Pessac Cedex, France |
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Abstract: | Many long-lived vertebrate species are under threat in the Anthropocene, but their conservation is hampered by a lack of demographic information to assess population long-term viability. When longitudinal studies (e.g., Capture-Mark-Recapture design) are not feasible, the only available data may be cross-sectional, for example, stranding for marine mammals. Survival analysis deals with age at death (i.e., time to event) data and allows to estimate survivorship and hazard rates assuming that the cross-sectional sample is representative. Accommodating a bathtub-shaped hazard, as expected in wild populations, was historically difficult and required specific models. We identified a simple linear regression model with individual frailty that can fit a bathtub-shaped hazard, take into account covariates, allow goodness-of-fit assessments and give accurate estimates of survivorship in realistic settings. We first conducted a Monte Carlo study and simulated age at death data to assess the accuracy of estimates with respect to sample size. Secondly, we applied this framework on a handful of case studies from published studies on marine mammals, a group with many threatened and data-deficient species. We found that our framework is flexible and accurate to estimate survivorship with a sample size of 300 . This approach is promising for obtaining important demographic information on data-poor species. |
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Keywords: | age at death Monte Carlo study regression survival analysis survivorship |
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