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  Access Rights: Use restricted to UNT Community
 Degree Discipline: Philosophy
 Collection: UNT Theses and Dissertations
A comparison of five robust regression methods with ordinary least squares: relative efficiency, bias and test of the null hypothesis

A comparison of five robust regression methods with ordinary least squares: relative efficiency, bias and test of the null hypothesis

Access: Use of this item is restricted to the UNT Community.
Date: August 2001
Creator: Anderson, Cynthia, 1962-
Description: A Monte Carlo simulation was used to generate data for a comparison of five robust regression estimation methods with ordinary least squares (OLS) under 36 different outlier data configurations. Two of the robust estimators, Least Absolute Value (LAV) estimation and MM estimation, are commercially available. Three authormodified variations on MM were also included (MM1, MM2, and MM3). Design parameters that were varied include sample size (n=60 and n=180), number of independent predictor variables (2, 3 and 6), outlier density (0%, 5% and 15%) and outlier location (2x,2y s, 8x8y s, 4x,8y s and 8x,4y s). Criteria on which the regression methods were measured are relative efficiency, bias and a test of the null hypothesis. Results indicated that MM2 was the best performing robust estimator on relative efficiency. The best performing estimator on bias was MM1. The best performing regression method on the test of the null hypothesis was MM2. Overall, the MM-type robust regression methods outperformed OLS and LAV on relative efficiency, bias, and the test of the null hypothesis.
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Burn and Sow: The Ethical Implications of Ecological Restoration

Burn and Sow: The Ethical Implications of Ecological Restoration

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Date: August 2005
Creator: Mauritz, Elizabeth
Description: Ecological restoration is quickly becoming a major approach to how humans interact with the natural world. Some view restoration as another land management technique on par with conservation and preservation. Others view it as a way to make reparations for our misdeeds and to reincorporate humans into the natural world. Ideas regarding restoration from key academics and restorationists are evaluated here. Their views have set the stage for the contemporary paradigm. Values that may be attributed to restoration and received from it are evaluated. I discuss my own reservations regarding potential problems with the product and practice of restoration. What is at stake regarding the involvement of people in restoration is examined, focusing on the different impacts volunteers and paid workers have on the value of the practice and outcome of the product.
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Ethics Naturally: An Environmental Ethic Based on Naturalness

Ethics Naturally: An Environmental Ethic Based on Naturalness

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Date: May 2004
Creator: Leard, Jason
Description: In this thesis I attempt to base an environmental ethic on a quality called naturalness. I examine it in terms of quantification, namely, as to whether it can quantified? I then apply the concept to specific areas such as restoration and conservation to create an environmental ethic and to show how such an ethic would be beneficial in general, and especially to policy issues concerning the environment. The thesis consists of three chapters: (1) the definition of nature and natural by way of a historical approach; (2) the place of humans in this scheme; and (3) the place of value and the discussion concerning quantification.
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