Defining, Evaluating, and Removing Bias Induced by Linear Imputation in Longitudinal Clinical Trials with MNAR Missing Data

Missing not at random (MNAR) post-dropout missing data from a longitudinal clinical trial result in the collection of “biased data”, which leads to biased estimators and tests of corrupted hypotheses. In a full rank linear model analysis the model equation, E[Y] = Xβ, leads to the definition of the primary parameter β = (X′X)−1X′E[Y], and the definition of linear secondary parameters of the form θ = Lβ = L(X′X)−1X′E[Y], including for example, a parameter representing a “treatment effect”. These parameters depend explicitly on E[Y], which raises the questions: what is E[Y] when some elements of the incomplete random vector Y are not observed and MNAR, or when such a Y is “completed” via imputation? We develop a rigorous, readily interpretable definition of E[Y] in this context that leads directly to definitions of β,Bias(β^)=E[β^]−β,Bias(θ^)=E[θ^ ]−Lβ, and the extent of hypothesis corruption. These definitions provide a basis for evaluating, comparing, and removing biases induced by various linear imputation methods for MNAR incomplete data from longitudinal clinical trials. Linear imputation methods use earlier data from a subject to impute values for post-dropout missing values and include “Last Observation Carried Forward” (LOCF) and “Baseline Observation Carried Forward” (BOCF), among others. We illustrate the methods of evaluating, comparing, and removing biases and the effects of testing corresponding corrupted hypotheses via a hypothetical, but very realistic longitudinal analgesic clinical trial

The Society and Its Environment. In: El Salvador: A Country Study.

This volume is one in a continuing series of books prepared by the Federal Research Division of the Library of Congress under the Country Studies/Area Handbook Program sponsored by the Department of the Army. The last two pages of this book list the other published studies. Most books in the series deal with a particular foreign country, describing and analyzing its political, economic, social, and national security systems and institutions, and examining the interrelationships of those systems and the ways they are shaped by cultural factors. The authors seek to provide a basic understanding of the observed society, striving for a dynamic rather than a static portrayal. Particular attention is devoted to the people who make up the society, their origins, dominant beliefs and values, their common interests and the issues on which they are divided, the nature and extent of their involvement with national institutions, and their attitudes toward each other and toward their social system and political order. The books represent the analysis of the authors and should not be construed as an expression of an official United States government position, policy, or decision. The authors have sought to adhere to accepted standards of scholarly objectivity. Corrections, additions, and suggestions for changes from readers will be welcomed for use in future editions

Observations on Political Ideology in Complex Societies in the Tropics-and Elsewhere.

A number of related themes are teased from the diverse essays composing this volume. The question of whether or not “the tropics” constitutes a unique setting for anthropological investigation is also briefly visited. The paper concludes with discussion of the basic ideological concept underlying the issue of political legitimacy in complex polities

Black Carib Domestic Organization in Historical Perspective: Traditional Origins of Contemporary Patterns.

In a highly influential study of the domestic organization of the Black Carib of Livingston, Guatemala, Nancie Gonzalez (1969) identified two basic household types characteristic of that population: one form, comprising 54.7 per cent of her sample, centered upon a married couple, with or without children; the other, comprising 45.3 per cent of her sample, focused upon consanguineal rather than affinal kinship ties (Gonzalez 1969:68). Gonzalez then related the high level of adaptability of these forms of domestic organization to contemporary economic conditions. In particular, she associated the high incidence of consanguineal households with conditions demanded by the migratory wage labor characteristic of this economic hinterland of eastern Central America

Sacred Landscapes and the Early Medieval European Cloister: Unity, Paradise, and the Cosmic Mountain

The architectural format of the early medieval monastery, a widespread feature of the Western European landscape, is examined from a cosmological perspective which argues that the garden, known as the garth, at the center of the cloister reconstructed the first three days of creational paradise as described in Genesis and, therefore, constituted the symbolic center of the cloister complex. The monastery is then further interpreted as representative of the cosmic mountain on whose summit paradise was believed to be situated. Outside its walls monasteries as symbolic mountains anchored and defined the focal points of the medieval European sacred landscape

Joseph the Smith and the Salvational Transformation of Matter in Early Medieval Europe

In early medieval Western Europe, Joseph, the earthly father of Jesus, was identified occupationally not only as a domestic woodworker but also as a blacksmith, the most mysterious, powerful, and sacrosanct category of supernaturally endowed skilled crafting known to traditional nonindustrial soci- eties. After reviewing skilled crafting and especially smithing as ritual processes, this essay considers typological identification of Joseph the smith as earthly parallel of the Deus artifex and as symbolic of the purifying (salvational) transformation of earthly matter (humanity) into a more rarefied (spiritual) state by fire as represented metaphorically by metallurgical processes. Aspects of the ideological climate of opinion encouraging such an identi- fication in the early Middle Ages are also discussed. [St. Joseph, transformation of matter, smithing, early medieval cosmology, metaphors of salvation]]]> 2006 English http://libres.uncg.edu/ir/uncg/f/M_Helms_Joseph_2006.pdf oai:libres.uncg.edu/10102 2014-02-17T06:00:41Z UNCG Before the Dawn: Monks and the Night in Late Antiquity and Early Medieval Europe Helms, Mary W. NC DOCKS at The University of North Carolina at Greensboro <![CDATA[Early European monks were preoccupied with the night. They were quintessential men of the dark, for nocturns, by far their longest liturgical office, was conducted each night, in the blackness of virtually unlit churches. In so doing monks not only ritually anticipated the coming of the dawn but also, and especially, engaged with the primordial cosmological darkness that preceded the original creation of Genesis. Various aspects of daily monastic life prepared monks for this primary nightly labor, the emotional and psychological effects of which were probably further heightened by physiological reactions to chronic sleep deprivation

The Purchase Society: Adaptation to Economic Frontiers.

A sociocultural category, termed the Purchase Society, is proposed as a framework within which to analyze adaptations by simpler societies living on the economic frontiers of both agrarian and industrializing states. Unlike peasantry, purchase societies maintain their political autonomy and are not enmeshed in the political controls characteristic of agrarian states. Consequently, their involvement with a wider society is characterized not by coercive demands for payment of various rents to the state, but solely by engagement in trade or wage labor to obtain items of foreign manufacture which have become cultural necessities. In order to participate successfully in this wider economic network, internal socio-political and economic structures may adapt in any number of ways so as to facilitate the formation of outside economic ties

Color and Creativity: Interpretation of Themes and Design Styles on a Panamanian Conte Bowl

To "outsiders" from the Western industrial world, indigenous art constitutes one of the most fascinating and enticing avenues into the conceptual worlds of indigenous peoples. This is certainly true for pre Columbian societies of the Americas, where artistry in stone, bone, wood, shell, ceramics, and metal encodes aspects of cosmologies and political ideologies that can greatly enhance both our intellectual understanding and our aesthetic appreciation of these ancient societies, provided we can "decode" the often enigmatic (to us) signs and symbols such sophisticated art portrays