Vitality Model

The vitality-based survival model is a parametric model for relating stressors and environmental properties to organism survivorship. Vitality is an abstract property which changes in response to organism experience. An organism's resistance to disease, level of stress, behavior, success and failure in feeding, frequency of predator attack, mating, parental care, and habitat choice all induce incremental changes in vitality. Mortality occurs when an organism's vitality reaches zero. Mortality can also occur independent of vitality through accidental-based mortality; catastrophic events occurring equally within a population and independent of the different past histories of the individuals. The model survival distribution is then the product of the probability of survival according to the organism's vitality and the probability of avoiding accidental mortality.

Papers

Anderson, J.J. 2000. A vitality based model relating stressors and environmental properties to organism survival - DRAFT.

• Final Publication: Anderson, J.J. 2000. vitality-based model relating stressors and environmental properties to organism survival. Ecological Monographs 70(3): 445-470.

Salinger, D.H., J.J. Anderson, and O.S. Hamel. 2003. A parameter estimation routine for the vitality-based survival model. Abstract.

• Final Publication: Salinger, D.H., J.J. Anderson, and O.S. Hamel. 2003. A parameter estimation routine for the vitality-based survival model. Ecological Modelling 166(3): 287-294.

S-PLUS Code and Data

• Vitality model parameter fitting code: VitalityModelFitting.SSC
  Code Release Date: Friday, 3 December 2004

• Instructions for using parameter fitting code: README

• Sample rainbow trout data file: RT.sdd

• Sample function call: RTtestScript.ssc

S-PLUS Code Change Log

• 12/3/2004 - Safeguarded against input of incremental mortality data with zero mortality in initial timestep.