Disease is often expected to limit host populations, but diseases do not always dramatically reduce host numbers and often have no effect. The impact of a fungal pathogen (Entomophaga grylli pathotype 1) on grasshopper (Camnula pellucida) populations was studied in a field experiment. We tested whether the effects of disease on grasshopper survival were additive, with disease mortality summing ...

REPORTRAPPORT Wild bootstrapping in finite populations with auxiliary Abstract Consider a nite population u, which can be viewed as a realization of a su-perpopulation model. A simple ratio model (linear regression, without intercept) with heteroscedastic errors is supposed to have generated u. A random sample is drawn without replacement from u. In this setup a two stage wild bootstrap resampl...

Widely used parametricgeneralizedlinearmodels are, unfortunately,a somewhat limited class of speciŽ cations. Nonparametric aspects are often introduced to enrich this class, resulting in semiparametricmodels. Focusingon single or k-sample problems,many classical nonparametricapproachesare limited to hypothesis testing.Those that allow estimation are limited to certain functionals of the underly...

The mortality rate dynamics between two related but different-sized populations are modeled consistently using a new stochastic mortality model that we call the gravity model. The larger population is modeled independently, and the smaller population is modeled in terms of spreads (or deviations) relative to the evolution of the former, but the spreads in the period and cohort effects between t...

Results of previous laboratory studies suggest that high population density often buffers the effects of chemical stressors that predominately increase mortality. Mortality stressors act to release more resources for the survivors and, therefore, produce less-than-additive effects. By contrast, growth stressors are expected to have opposite results or more-than-additive effects. We investigated...

The intrinsic population growth rate (r) of the surplus production function used in the biomass dynamic model and the steepness (h) of the stock-recruitment relationship used in age-structured population dynamics models are two key parameters in fish stock assessment. There is generally insufficient information in the data to estimate these parameters that thus have to be constrained. We develo...

This study examines aggregate county income growth across the 48 contiguous states from 1990 to 2005. To control for endogeneity we estimate a two-stage spatial error model and infer parameter significance by implementing a number of spatial bootstrap algorithms. We find that outdoor recreation and natural amenities favor positive growth in rural counties, densely populated rural areas enjoy st...

We analyzed population dynamics and changes in species diversity and composition of saplings (tree or shrub stems >50 cm in height and < 1 cm diameter at breast height) during an interval lasting from 5 years before the 1996 Hurricane Fran to 5 years post-hurricane through use of permanent transects where individual sapling stems were censused annually. The study site was the Duke Forest, locat...

We have conducted visual analysis using Health Nutirition and Population Statistics data set found on The World Bank web page. The data set provides key health, nutrition and population statistics gathered from more than 100 countries and more than 255 data items, covering from 1960 to 2009. Among all the data, we decided to look into relationship between countries’ health expenditure with vari...

E-mail: [email protected] The main goal of our study is to describe and to interpret the selected features of demographic behaviour after the regime change. We compare two countries and three populations – the Hungarians in Hungary, the Romanian population, and the Hungarian population living in Transylvania. We are interested in similarities and differences in fertility trends, partnership ...