Physical Sciences and Mathematics Commons^™

A Corrected Pseudo-Score Approach For Additive Hazards Model With Longitudinal Covariates Measured With Error, Xiao Song, Yijian Huang

UW Biostatistics Working Paper Series

In medical studies, it is often of interest to characterize the relationship between a time-to-event and covariates, not only time-independent but also time-dependent. Time-dependent covariates are generally measured intermittently and with error. Recent interests focus on the proportional hazards framework, with longitudinal data jointly modeled through a mixed effects model. However, approaches under this framework depend on the normality assumption of the error, and might encounter intractable numerical difficulties in practice. This motivates us to consider an alternative framework, that is, the additive hazards model, under which little has been done when time-dependent covariates are measured with error. We propose …

Conference Summary: Water, Climate And Uncertainty: Implications For Western Water Law, Policy, And Management, Steve Bailey

Water, Climate and Uncertainty: Implications for Western Water Law, Policy, and Management (Summer Conference, June 11-13)

7 pages.

"Steve Bailey, National Center for Atmospheric Research"

Longevity Of A Woodhouse's Toad, Richard M. Engeman, Melvin A. Engeman

USDA Wildlife Services: Staff Publications

We follow up a report on a male Woodhouse's toad (Bufo woodhousii) that had been observed since 1978 (Engeman RM, Engeman EM. 1996. Longevity of Woodhouse's toad in Colorado. Northwestern Naturalist 77:23). The toad had found its way into, and remained in, a basement window-well of a brick home in an unincorporated western suburb of Denver, Colorado. This property has recently changed hands, and access for future monitoring of the toad's survival is uncertain. Thus, we report its longevity as of 2002.

A Model Life Table For Bottlenose Dolphins (Tursiops Truncatus) From The Indian River Lagoon System, Florida, U.S.A., Megan K. Stolen, Jay Barlow

United States Department of Commerce: Staff Publications

Data gathered from 220 stranded bottlenose dolphins (Tzmiop tvuncatlls) in the Indian River Lagoon system, Florida, were used to derive a life table. Survivorship curves were fit to the data using Siler’s competing-risk model and a maximum likelihood approach. Population growth was estimated to be between r = 0.0 and 0.046 based on the observed numbers of stranded dolphins. Variance in survival rates was estimated using an individual-based, age-structured population projection model. We estimate that the overall annual mortality rate for this population was 9.8% per year. Sex-specific differences in survivorship were apparent with females outliving males. The …

Survival Rates And Recovery Distributions Of Canada Geese Banded In Nebraska, Larkin A. Powell, Mark Vrtiska, Nick Lyman

School of Natural Resources: Faculty Publications

We analyzed banding and recovery data for Canada geese (Branta canadensis) banded in Nebraska during 1990–2000. Survival rates were lower during 1996–2000 (adult: 0.688, SE = 0.016; juvenile: 0.611, SE = 0.029), than 1990–1995 (adult: 0.727, SE = 0.011; juvenile: 0.639, SE = 0.024). Average juvenile-to-adult ratio from banding data was 0.834 (SD = 0.485), resulting in an annual population growth rate (λ) estimate for 1990–1995 of 0.995 (95% CI = 0.021), and 0.922 (0.018) for 1996–2000. Our recovery analysis suggests that 67% of geese banded in Nebraska are shot in Nebraska. Over 30% of both juvenile and adult recoveries …

Restoration And Monitoring Of The River Otter Population In Iowa, J. A. Pitt, W. R. Clark, R. D. Andrews, K. P. Schlarbaum, D. D. Hoffman, S. W. Pitt

Journal of the Iowa Academy of Science: JIAS

Northern river otters (Lontra canadensis) were widespread in North America at the time of European settlement. However, river otters were extirpated from most of Iowa in the early 1900s due to habitat degradation and unregulated harvest. In 1985, the Iowa Department of Natural Resources began an effort to restore the river otter population throughout the state, including a pilot study of survival to determine if establishment was feasible. Annual survival was estimated to be 86% during the pilot study. River otters dispersed an average of about 11 km from the point of release and exhibited habitat use typical for the …

Quantifying Habitat Quality Of Larval Bay Anchovy (Anchoa Mitchilli) In Chesapeake Bay By Linking An Individual-Based Model With Spatially-Detailed Field Data, Aaron Thomas Adamack

LSU Master's Theses

Larval bay anchovy (Anchoa mitchilli) habitat quality in Chesapeake Bay was predicted using an individual-based model applied to spatially-detailed field data from Rilling and Houde (1999). Habitat quality was predicted using the ratio of instantaneous mortality rate to instantaneous growth rate. Model predictions of habitat quality were compared to field estimates of habitat quality derived from the spatially-detailed field data. Three sets of one-day simulations were performed to estimate larval growth and mortality rates throughout Chesapeake Bay during June and during July 1993. Field-based simulations used field data to estimate the model inputs of water temperature, zooplankton densities, and the …