Modeling Unobserved Sources of Heterogeneity in Animal Abundance Using a Dirichlet Process Prior
Version of Record online: 28 JUN 2008
© 2008, The International Biometric Society
Volume 64, Issue 2, pages 635–644, June 2008
How to Cite
Dorazio, R. M., Mukherjee, B., Zhang, L., Ghosh, M., Jelks, H. L. and Jordan, F. (2008), Modeling Unobserved Sources of Heterogeneity in Animal Abundance Using a Dirichlet Process Prior. Biometrics, 64: 635–644. doi: 10.1111/j.1541-0420.2007.00873.x
- Issue online: 28 JUN 2008
- Version of Record online: 28 JUN 2008
- Received May 2006. Revised April 2007. Accepted May 2007.
- Abundance heterogeneity;
- Bayesian nonparametrics;
- Empirical Bayes;
- Model uncertainty;
- Okaloosa darter;
- Removal sampling
Summary In surveys of natural populations of animals, a sampling protocol is often spatially replicated to collect a representative sample of the population. In these surveys, differences in abundance of animals among sample locations may induce spatial heterogeneity in the counts associated with a particular sampling protocol. For some species, the sources of heterogeneity in abundance may be unknown or unmeasurable, leading one to specify the variation in abundance among sample locations stochastically. However, choosing a parametric model for the distribution of unmeasured heterogeneity is potentially subject to error and can have profound effects on predictions of abundance at unsampled locations. In this article, we develop an alternative approach wherein a Dirichlet process prior is assumed for the distribution of latent abundances. This approach allows for uncertainty in model specification and for natural clustering in the distribution of abundances in a data-adaptive way. We apply this approach in an analysis of counts based on removal samples of an endangered fish species, the Okaloosa darter. Results of our data analysis and simulation studies suggest that our implementation of the Dirichlet process prior has several attractive features not shared by conventional, fully parametric alternatives.