Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
Browse
2 results
Search Results
Item Two Goodness-of-Fit Tests for the Density Ratio Model(2017) Yu, Luquan; Kedem, Benjamin; Mathematical Statistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Under consideration are goodness-of-fit tests for the \textit{density ratio model}. The model stipulates that the log-likelihood ratio of two unknown densities is of a known form which depends on finite dimensional parameters and a tilt function. We can derive the empirical distribution estimator $\tilde{G}$ from a reference sample, and the semiparametric distribution estimator $\hat{G}$ under the density ratio model. Furthermore we can derive kernel density estimators $\tilde{g}$ and $\hat{g}$ corresponding to $\tilde{G}$ and $\hat{G}$ by choosing a bandwidth parameter. Goodness-of-fit test statistics can be constructed via the discrepancy between $\tilde{g}$ and $\hat{g}$ using Hellinger distance and a modification thereof. We propose two new test statistics by modifying the goodness-of-fit test statistics suggested by Bondell (2007) and by Cheng and Chu (2004). Asymptotic results and limiting distributions are derived for both new test statistics, and the selections of the kernel and bandwidth are discussed. Monte-Carlo simulations show that the new test statistics improve the accuracy of the the goodness-of-fit test and that the limiting distributions of the new test statistics are more symmetric.Item Resource and space use in the wild golden lion tamarin, Leontopithecus rosalia(2008-11-11) Hankerson, Sarah; Dietz, James M; Behavior, Ecology, Evolution and Systematics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Animals move through their environment in response to resource, competitor, and predator distribution. In this dissertation I examine resource and space use in wild golden lion tamarins (GLTs, Leontopithecus rosalia). In chapter one I present the results of a field study exploring factors predicting sleeping site selection. GLTs preferentially slept in tree holes. Each group had a few frequently used sites typically found in large, living trees on hillsides near other large trees. Topography and smallscale forest and tree variables were better than habitat-level classifications in predicting sleeping site use. In my second chapter I evaluated home range calculation methods. Using 19 years of data for 15 groups of GLTs, I calculated a yearly home range for each group with the three most commonly used methods: minimum convex polygon (MCP), grid cell, and kernel density estimates. MCP produced the largest home range estimates, grid cell the smallest, and kernel estimates were intermediary. Kernel estimates were preferred because probability of use may be calculated for any part of the home range, there is high concordance between observation spatial distribution and home range shape, and there is a lack of relationship between sample size and home range size. In my third chapter I tested three hypotheses explaining home range size in group-dwelling animals. First, I tested the dominant hypothesis, which states that home range size is determined by group energetic needs and, therefore, group size. The second and third hypotheses relate to numbers of adult females and males present in groups. More adults may increase ranging because of increased reproduction, search for breeding opportunities, or defense. I also examined how variation in predation affects population density and demography and, thus, mediates space use. I found support for all three hypotheses. Larger ranges were occupied by groups that were large, had two breeding females, and/or more potentially breeding males or adult natal males. Intense predation resulted in lower population densities, smaller groups, only one breeding female per group, and fewer adult natal males. Population density and predation had significant, negative impacts on home range size.